List all web parts that have been used on site pages in a given SharePoint Online site. Legacy approach.

Microsoft-SharePoint-Get-SPWebPartsOnPage.ps1

# Connect to SPO (see seperate connect function - https://gist.github.com/jcallaghan/d61d4bd8d23fbadf9687434a0a49dd2d)
$context = Connect-SPO -url "https://tenant.sharepoint.com//"

# Get web
$web = $context.Web
$context.Load($web)
$context.ExecuteQuery()
Write-Host "Processing web with URL: '$($web.Url)'" 

# Get pages library
$list = $context.web.Lists.GetByTitle("Pages") 
$context.Load($List)
$context.ExecuteQuery()

# Get files from pages library
$pages = $list.RootFolder.Files
$context.Load($pages)
$context.ExecuteQuery()

# Get particular page
$page = $pages | Where {$_.Name -eq "AllItems.aspx"}
$context.Load($page)
$context.ExecuteQuery()

# Get web part manager
$wpm = $page.GetLimitedWebPartManager([Microsoft.SharePoint.Client.WebParts.PersonalizationScope]::Shared)  
$context.Load($wpm)
$context.ExecuteQuery()

# Get web parts
$webparts = $wpm.WebParts
$context.Load($WebParts)
$context.ExecuteQuery()

if($webparts.Count -gt 0){  
    Write-Host "Looping through all webparts..."  
    foreach($webpart in $webparts){  
        # Get web part properties
        $wpProperties = $webpart.WebPart.Properties.FieldValues  
        write-host "Web Part: $($webpart.ID) $($wpProperties.Title)"
    }
}