A PowerShell script that uses Sitecore PowerShell Extensions to extract Sitecore items data to CSV and then use CSV to import data into Sitecore Items.

Export-SitecoreItemData.ps1

<#
    .SYNOPSIS
       Generic Page data extraction
       
    .DESCRIPTION
        Gets Sitecore Items from legacy database and extracts field values.
        List could be exported to csv by OOTB feature of List View in SPE.
        
    .NOTES
        Akash Borkar 
#>

function Write-LogExtended {
param(
[string]$Message,
[System.ConsoleColor]$ForegroundColor = $host.UI.RawUI.ForegroundColor,
[System.ConsoleColor]$BackgroundColor = $host.UI.RawUI.BackgroundColor
)
    Write-Log -Object $message
    Write-Host -Object $message -ForegroundColor $ForegroundColor -BackgroundColor $backgroundColor
}

# Function for getting item names from pipe-separated item ids
function GetItemNamesFromIds {
param(
[System.String] $ids
)
if($ids.Contains("|"))
{
# Split the string by pipe and clean up each GUID
        $guids = $ids.Split("|")| ForEach-Object { $_.Trim(' {}')}
[Sitecore.Text.ListString]$nameArr = ""
foreach($id in $guids){
            $formattedId = "{0}{1}{2}" -f '{', $id, '}'
            $Id = [Sitecore.Data.ID]::Parse($formattedId)
            $item = Get-Item -Path xyz: -ID $Id
if($item -ne $null -and !$nameArr.Contains($item.Name)){
                $nameArr.Add($item.Name)| Out-Null
}
}
# Join the names with pipe separator and return the result
        $names = [System.String]::Join("|", $nameArr)
return $names
}
else
{
        $item = Get-Item -Path xyz: -ID $ids
return $item.Name
}
}

#Function for getting datasource item, which is further used for extracting field value & assigning to new rendering
function Get-DatasourceItem{
param(
[System.String] $path
)
        $datasourceItem = $sourceDatabase.GetItem($path)
return $datasourceItem
}


Write-LogExtended "Generic Pages Data Extraction"
Write-LogExtended "-----------------------------------------------------------------"
$processedItems = [System.Collections.Generic.List[PSCustomObject]]::new()
$nonprocessedItems = [System.Collections.Generic.List[PSCustomObject]]::new()
$sourceDatabase = Get-Database "xyz"
$parentPath = Show-Input -Prompt "Please enter the Sitecore item path for getting children"
if($parentPath -ne $null)
{
    Write-Host "Selected path: $parentPath"
    #Get all child items based on provided path. /sitecore/content/XYZ/Home/Generic
    $nodePath = "xyz:" + $parentPath
    $items = Get-ChildItem -Path $nodePath -Recurse | Where-Object { $_.TemplateName -eq 'Generic Page'}
    Write-LogExtended "Total child items: $($items.Count)  Path: $($nodePath)" -ForegroundColor Green

foreach($sourceItem in $items)
{
if($sourceItem -ne $null){
#Retrieve RTE
$rts = Get-Rendering -Item $sourceItem -Device $defaultLayout -FinalLayout | Where-Object { $_.ItemID -eq "{278F7B0D-98F4-4873-9B7B-940082158E4A}"}
[Sitecore.Text.ListString]$rtArr = ""
if($rts -ne $null)
{
foreach($rt in $rts)
{
$item = $sourceDatabase.GetItem($rt.Datasource)
if($item -ne $null -and $item["Text"] -ne "")
{
    $rtArr.Add($item["Text"])| Out-Null
}
}
}

#Retrieve Accordion
$accordion = Get-Rendering -Item $sourceItem -Device $defaultLayout -FinalLayout | Where-Object { $_.ItemID -eq "{165B5ECC-E6A0-4B41-AA23-D28FA5A9BF68}"}
$accordionCount = 0
[Sitecore.Text.ListString]$titleArr = ""
[Sitecore.Text.ListString]$descArr = ""
if($accordion -ne $null)
{
    foreach($renderingItem in $accordion)
    {
      if($renderingItem.Datasource -ne "")
      {
          $rendering = Get-Item -Path xyz: -Id $renderingItem.Datasource
        if($rendering.HasChildren)
        {
           $accdChildItems = Get-ChildItem -Path xyz: -ID $rendering.ID
           foreach($item in $accdChildItems)
           {
            if($item["Title"] -ne "" -and $item["Description"] -ne "")
            {
                  $titleArr.Add($item["Title"])| Out-Null
                  $descArr.Add($item["Description"])| Out-Null
            }
           }
                            $accordionCount++;
        }
       }
    }
}

#Retrieve values of multilist field named Categories
            $categories = $sourceitem["Categories"]
            $categoriesnames = ""
if($categories -ne "" -and $categories -ne $null)
{
    $categoriesnames = GetItemNamesFromIds -ids $categories
}
try{
                $processedItems.Add(
                [PSCustomObject]@{
                        Name = $sourceItem.Name
                        Id = $sourceItem.Id
                        Path = $sourceItem.Paths.FullPath
                        Title = $sourceItem["Title"]
                        HeaderTitle = $sourceItem["Header Title"]
                        Summary = $sourceItem["Summary"]
                        Image = $sourceItem["Image"]
                        OGImage = $sourceItem["Media Image"]
                        Categories = $categoriesnames
                        HasRTE = $rtArr.Count
                        RichText1 = $richText
                        RichText2 = $rtArr[1]
                        RichText3 = $rtArr[2]
                        HasAccordion = $accordionCount
                        AccTitle1 = $titleArr[0]
                        AccDesc1 = $descArr[0]
                        AccTitle2 = $titleArr[1]
                        AccDesc2 = $descArr[1]
                        AccTitle3 = $titleArr[2]
                        AccDesc3 = $descArr[2]
                        AccTitle4 = $titleArr[3]
                        AccDesc4 = $descArr[3]
}
)
  Write-LogExtended "Added data for $($sourceItem.Name), Path: $($sourceItem.Paths.FullPath) " -ForegroundColor Green
}
catch{
                Write-Host "Error occured" -BackgroundColor DarkRed
                $nonprocessedItems.Add(
                [PSCustomObject]@{
                        Name = $sourceItem.Name
                        Id = $sourceItem.Id
                        Path = $sourceItem.Paths.FullPath
}
)
}
}
else
{
  Write-LogExtended "No Item found in csv for SourceURL: $($row.SourceURL)" -ForegroundColor RED
}
}
    $processedItems | Show-ListView -PageSize 15000 -Property  Name, Id, Path, Title, HeaderTitle, Summary, Categories, Image, OGImage, 
                                                               HasRTE, RichText1, RichText2, RichText3, HasAccordion, AccTitle1, AccDesc1, AccTitle2, AccDesc2, AccTitle3, 
                                                               AccDesc3, AccTitle4, AccDesc4
    $processedItems | export-csv -Path "C:\inetpub\wwwroot\App_Data\Process.csv" -NoTypeInformation                                                  
    $nonprocessedItems | Show-ListView -PageSize 15000 -Property  Name, Id, Path
}
else
{
        Write-Host "Path is not provided : $parentPath"
}

Import-SitecoreItemData.ps1

<#
    .SYNOPSIS
       Generic Pages Import
       
    .DESCRIPTION
        Iterate through CSV, create siteore items for generic pages and Populate fields. Generate List of processed and Non processed items.
        By default, packages are saved to disk at C:\inetpub\wwwroot\App_Data\packages. Thus C:\inetpub\wwwroot\App_Data\GenericPages.csv will be
        path
    
    .NOTES
        Akash Borkar 
#>

functionWrite-LogExtended{
param(
[string]$Message,
[System.ConsoleColor]$ForegroundColor = $host.UI.RawUI.ForegroundColor,
[System.ConsoleColor]$BackgroundColor = $host.UI.RawUI.BackgroundColor
)
Write-Log -Object $message
Write-Host -Object $message -ForegroundColor $ForegroundColor -BackgroundColor $backgroundColor
}


Write-LogExtended"Generic Pages Import"
Write-LogExtended"-----------------------------------------------------------------"
# Prompt for the file path
$filePath = Show-Input -Prompt "Please enter the full path to the CSV file"
if($filePath -ne $null)
{
Write-Host"Selected file: $filePath"

# Import the CSV file
$csvData = Import-Csv -Path $filePath | Where-Object{ -join $_.psobject.Properties.Value }
Write-LogExtended"CSV file read successfully" -ForegroundColor Green
if($csvData -ne $null)
{
$processedItems = [System.Collections.Generic.List[PSCustomObject]]::new()
$NonProcessedItems = [System.Collections.Generic.List[PSCustomObject]]::new()
$database = Get-Database"master"
$placeholder = "/headless-main/container-1"
foreach($rowin$csvData){
#Generic Page branch
$branchTemplateId = [Sitecore.Data.ID]::Parse("{8032FE9E-3CD1-4E80-8377-66BBF74F839E}")

# Extract the desired item name, parent item and template id from the URL
$itemName = $row.Name
$parentItemPath = $row.Path -Replace $itemName, ""

# Get the parent item
$parentItem = $database.GetItem($parentItemPath)
if($parentItem)
{
# Check if the item already exists
$existingItemPath = "$($parentItem.Paths.FullPath)/$itemName"
$itemExists = Test-Path -Path $existingItemPath
if(-not $itemExists)
{
$item = [Sitecore.Data.Managers.ItemManager]::AddFromTemplate($itemName, $branchTemplateId, $parentItem)
if($item -eq $null)
{
Write-LogExtended"Unable to create new item - $($itemName) - in Language en" -ForegroundColor Red
      $NonProcessedItems.Add(
      [PSCustomObject]@{
       ID = $row.ID
       Name    = $row.Name
       Path = $row.Path
})
}

if($item -ne $null){
$item.Editing.BeginEdit()
$item["Title"] = $row.Title

#Meta Properties/OG
$item["OpenGraphTitle"] = $row.Title
$item["OpenGraphDescription"] = $row.Summary
$item["MetaDescription"] = $row.Summary
$item["TwitterDescription"] = $row.Summary 
$item["TwitterImage"] = $row.OGImage
$item.Editing.EndEdit() | Out-Null

$datasourcePath =  $item.Paths.FullPath + "/Data/"
#Create and Populate Rich Text (Max RT are 3 as we had extracted 3 RTEs)
if($row.RichText1 -ne "")
{
For($i=1; $i -lt 4; $i++)
{
$propname = "RichText$i"
if($row.$propname -ne "")
{
$dsitem = New-Item -Path $datasourcePath -Name "Text $i" -ItemType "{4FBDBF79-C7D6-42F1-8048-D5E70D6167D5}"
$dsitem.Editing.BeginEdit()
$dsitem.Text =  $row.$propname
$dsitem.Editing.EndEdit() | Out-Null
#Create and Set Rich text Rendering
$rendering = get-item -path master: -id {EF82E4AE-C274-40D4-837C-B3E1BF180CCC}
$renderinginstance = $rendering | new-rendering -placeholder $placeholder
$renderinginstance.datasource = $dsitem.id
Add-Rendering -Item $item -placeholder $placeholder -instance $renderinginstance -finallayout
$item.Editing.beginedit()
$item.Editing.endedit() | out-null
}
}
}

#Create and Populate Accordion datasource item (Max Acc are 4)
if($row.AccTitle1 -ne "" -and $row.AccDesc1 -ne "")
{
$accDatasourcePath =  $item.Paths.FullPath + "/Data/"
#Accordion
$Accitem = New-Item -Path $accDatasourcePath -Name "Accordion" -ItemType "{D482D45C-4248-46C8-BDD5-DE7C2255C52A}"
$Accitem.Editing.BeginEdit()
$Accitem.Title =  "Accordion"
$Accitem.Editing.EndEdit() | Out-Null
#Create and Set Acc rendering
$rendering = Get-Item -Path master: -ID {3341A94D-42C9-4EE3-8A25-51D8B437982B}#Accordion
$renderingInstance = $rendering | New-Rendering -Placeholder $placeholder
$renderingInstance.Datasource = $Accitem.ID
Add-Rendering -Item $item -PlaceHolder $placeholder -Instance $renderingInstance -FinalLayout
For($i=1; $i -lt 5; $i++)
{
$titlename = "AccTitle$i"
$descname = "AccDesc$i"
if($row.$titlename -ne "" -and $row.$descname -ne "")
{
#Acc Panel
$dsitem = New-Item -Path $Accitem.Paths.FullPath -Name $row.$titlename -ItemType "{B50C502C-2740-44C8-A63E-E9E4AF4BAA4B}"
$dsitem.Editing.BeginEdit()
$dsitem.Title =  $row.$titlename
$dsitem.Content =  $row.$descname
$dsitem.Editing.EndEdit() | Out-Null
#Create and Set Acc panel rendering
$rendering = Get-Item -Path master: -ID {7614DFFF-6735-4BA5-929A-A82FBC91DB25}#Acc Panel
$renderingInstance = $rendering | New-Rendering -Placeholder "/headless-main/container-1/accordion-panels-1"
$renderingInstance.Datasource = $dsitem.ID
Add-Rendering -Item $item -PlaceHolder "/headless-main/container-1/accordion-panels-1" -Instance $renderingInstance -FinalLayout
$item.Editing.BeginEdit()
$item.Editing.EndEdit() | Out-Null
Write-LogExtended"Added Accordion datasource to New Item - $($item.Name) at $($dsitem.Paths.FullPath)" -ForegroundColor Green
}
}
}

$ManualWork = "No"
if(($row.HasRTE -gt 3) -or($row.HasAccordion -gt 4))
{
$ManualWork = "Yes"
}

Write-LogExtended"Created New Item - $($itemName) at $($parentItemPath)" -ForegroundColor Green
                    $processedItems.Add(
                    [PSCustomObject]@{
                            Name    = $item.Name
                            Id = $item.ID
                            NewPath = $item.Paths.FullPath
                            HasRTE = $row.HasRTE
                            HasAccordion = $row.HasAccordion
                            ManualWork = $ManualWork
})
}
}
else
{
Write-LogExtended"Item $($itemName) already exists at $($parentItemPath) " -ForegroundColor Yellow
}
}
else
{
Write-LogExtended"Parent item not found: $parentItemPath" -ForegroundColor Red
}
}

$processedItems | Show-ListView -PageSize 2000 -InfoTitle "Processed Items" -Property  Name, Id, NewPath, HasRTE, HasAccordion, ManualWork
$processedItems | export-csv -Path "C:\inetpub\wwwroot\App_Data\GenericPagesReport.csv" -NoTypeInformation
$NonProcessedItems | Show-ListView -PageSize 2000 -InfoTitle "Non Processed Items" -Property  ID, Name, Path
}
}
else
{
Write-Host"No file selected : $filePath"
}