Created this to extract information from diskpart. As of this writing, it supports the following disk part commands: "list disk", "list partition", "list volume", "shrink querymax", "detail disk"

DiskPartPowerShell.psm1

function Parse-SizeUnit {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory=$true, Position=0, ValueFromPipeline=$true)][string]$SizeUnit
    )

    $SizeUnit = $SizeUnit.Trim()
    
    $Size = 0;
    $Unit = 'B';

    if ($SizeUnit -match '\d+\s+\w*B$') {
        $SizeUnitSplit = $SizeUnit -split '\s+'
        $Size = [int]$SizeUnitSplit[0]
        $Unit = $SizeUnitSplit[1]
    } elseif ($SizeUnit -match '\d+\w*B$')  {
        $SizeUnit -match '\d+'
        $Size = [int]$Matches[0]
        $SizeUnit -match '\D+\w*B$'
        $Unit = $Matches[0]
    }

    if ($Unit -eq 'TB') {
        $Size * 1TB
    } elseif ($Unit -eq 'GB') {
        $Size * 1GB
    } elseif ($Unit -eq 'MB') {
        $Size * 1MB
    } elseif ($Unit -eq 'KB') {
        $Size * 1KB
    } elseif ($Unit -eq 'B') {
        $Size
    } else { 0 }
}

function List-Disk {
    $DiskArray = 'list disk' | diskpart | Where-Object { $_ -match 'Disk .+' } 

    $HeaderRow = $DiskArray | Where-Object { $_ -match 'Disk ### .*' } | Select -First 1

    $DiskNumberIndex = $HeaderRow.IndexOf('###')
    $StatusIndex = $HeaderRow.IndexOf('Status')
    $SizeIndex = $HeaderRow.IndexOf('Size')
    $FreeIndex = $HeaderRow.IndexOf('Free')
    $DynamicIndex = $HeaderRow.IndexOf('Dyn')
    $GptIndex = $HeaderRow.IndexOf('Gpt')
    
    $DiskArray | Select -Skip 1 | ForEach-Object {
        New-Object PSObject -Property @{
            Number = [int]$_.SubString($DiskNumberIndex, 3).Trim();
            Status = $_.SubString($StatusIndex, 13).Trim();
            Size = Parse-SizeUnit $_.SubString($SizeIndex, 7).Trim();
            Free = Parse-SizeUnit $_.SubString($FreeIndex, 7).Trim();
            IsDynamic = $_.SubString($DynamicIndex, 3).Trim() -eq '*';
            IsGpt = $_.SubString($GptIndex).Trim() -eq '*';
            PartitionStyle = If ($_.SubString($GptIndex).Trim() -eq '*') {'GPT'} Else {'MBR'};
        }
    }
}

function List-Partition {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory=$true, Position=0, ValueFromPipeline=$true)][int]$DiskNumber
    )

    $PartitionArray = "select disk $($DiskNumber)", "list partition" | diskpart | Where-Object { $_ -match 'Partition .+' }

    $HeaderRow = $PartitionArray | Where-Object { $_ -match 'Partition ### .*' } | Select -First 1

    $PartitionNumberIndex = $HeaderRow.IndexOf('###')
    $TypeIndex = $HeaderRow.IndexOf('Type')
    $SizeIndex = $HeaderRow.IndexOf('Size')
    $OffsetIndex = $HeaderRow.IndexOf('Offset')

    $PartitionArray | Select -Skip 1 | ForEach-Object {
        New-Object PSObject -Property @{
            Number = [int]$_.SubString($PartitionNumberIndex, 3).Trim();
            Type = $_.SubString($TypeIndex, 16).Trim();
            Size = Parse-SizeUnit $_.SubString($SizeIndex, 7).Trim();
            Offset = Parse-SizeUnit $_.SubString($OffsetIndex).Trim();
        }
    }
}

function List-Volume {
    $VolumeArray = 'list volume' | diskpart | Where-Object { $_ -match 'Volume .+' } 

    $HeaderRow = $VolumeArray | Where-Object { $_ -match 'Volume ### .*' } | Select -First 1

    $VolumeNumberIndex = $HeaderRow.IndexOf('###')
    $LetterIndex = $HeaderRow.IndexOf('Ltr')
    $LabelIndex = $HeaderRow.IndexOf('Label')
    $FileSystemIndex = $HeaderRow.IndexOf('Fs')
    $TypeIndex = $HeaderRow.IndexOf('Type')
    $SizeIndex = $HeaderRow.IndexOf('Size')
    $StatusIndex = $HeaderRow.IndexOf('Status')
    $InfoIndex = $HeaderRow.IndexOf('Info')

    $VolumeArray | Select -Skip 1 | ForEach-Object {
        New-Object PSObject -Property @{
            Number = [int]$_.SubString($VolumeNumberIndex, 3).Trim();
            Letter = $_.SubString($LetterIndex, 3).Trim();
            Label = $_.SubString($StatusIndex, 11).Trim();
            FileSystem = $_.SubString($FileSystemIndex, 5).Trim();
            Type = $_.SubString($TypeIndex, 10).Trim();
            Size = Parse-SizeUnit $_.SubString($SizeIndex, 7).Trim();
            Status = $_.SubString($StatusIndex, 9).Trim();
            Info = $_.SubString($InfoIndex).Trim();
        }
    }
}

function Get-ShrinkQueryMax {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory=$true, Position=0, ValueFromPipeline=$true)][string]$DriveLetter
    )

    "select volume $($DriveLetter)", "shrink querymax" | diskpart | 
    Where-Object { $_ -match 'The maximum number of reclaimable bytes is:.+' } | 
    ForEach-Object { $_ -split ':' } | Select-Object -Skip 1 | ForEach-Object {
        Parse-SizeUnit $_.Trim()
    }
}

function Get-DetailDisk {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory=$true, Position=0, ValueFromPipeline=$true)][int]$DiskNumber
    )

    $DiskDetails = "select disk $($DiskNumber)", "detail disk" | diskpart

    $Disk = New-Object PSObject -Property @{
        DiskId = '';
        Type = '';
        Status = '';
        Path = 0;
        Target = 0;
        LunId = 0;
        LocationPath = '';
        CurrentReadOnlyState = '';
        ReadOnly = '';
        BootDisk = '';
        PagefileDisk = '';
        HibernationFileDisk = '';
        CrashdumpDisk = '';
        ClusteredDisk = '';
        Volumes = $null;
    }

    $DiskDetails | ForEach-Object {
        if ($_ -match 'Disk ID:') {
            $DiskIdParts = $_ -split ':'
            $Disk.DiskId = $DiskIdParts[1].Trim()
        } elseif ($_ -match 'Type\s+:') {
            $TypeParts = $_ -split ':'
            $Disk.Type = $TypeParts[1].Trim()
        } elseif ($_ -match 'Status\s+:') {
            $StatusParts = $_ -split ':'
            $Disk.Status = $StatusParts[1].Trim()
        } elseif ($_ -match 'Path\s+:') {
            $PathParts = $_ -split ':'
            $Disk.Path = $PathParts[1].Trim()
        } elseif ($_ -match 'Target\s+:') {
            $TargetParts = $_ -split ':'
            $Disk.Target = $TargetParts[1].Trim()
        } elseif ($_ -match 'LUN ID\s+:') {
            $LunIdParts = $_ -split ':'
            $Disk.LunId = $LunIdParts[1].Trim()
        } elseif ($_ -match 'Location Path\s+:') {
            $LocPathParts = $_ -split ':'
            $Disk.LocationPath = $LocPathParts[1].Trim()
        } elseif ($_ -match 'Current Read-only State\s+:') {
            $CurrROStateParts = $_ -split ':'
            $Disk.CurrentReadOnlyState = $CurrROStateParts[1].Trim()
        } elseif ($_ -match 'Read-only\s+:') {
            $ReadOnlyParts = $_ -split ':'
            $Disk.ReadOnly = $ReadOnlyParts[1].Trim()
        } elseif ($_ -match 'Boot Disk\s+:') {
            $BootDiskParts = $_ -split ':'
            $Disk.BootDisk = $BootDiskParts[1].Trim()
        } elseif ($_ -match 'Pagefile Disk\s+:') {
            $PagefileDiskParts = $_ -split ':'
            $Disk.PagefileDisk = $PagefileDiskParts[1].Trim()
        } elseif ($_ -match 'Hibernation File Disk\s+:') {
            $HibFileDiskParts = $_ -split ':'
            $Disk.HibernationFileDisk = $HibFileDiskParts[1].Trim()
        } elseif ($_ -match 'Crashdump Disk\s+:') {
            $CrashdumpDiskParts = $_ -split ':'
            $Disk.CrashdumpDisk = $CrashdumpDiskParts[1].Trim()
        } elseif ($_ -match 'Clustered Disk\s+:') {
            $ClusteredDiskParts = $_ -split ':'
            $Disk.ClusteredDisk = $ClusteredDiskParts[1].Trim()
        }
    }

    $VolumeArray = $DiskDetails | Where-Object { $_ -match 'Volume .+' } 

    $HeaderRow = $VolumeArray | Where-Object { $_ -match 'Volume ### .*' } | Select -First 1

    $VolumeNumberIndex = $HeaderRow.IndexOf('###')
    $LetterIndex = $HeaderRow.IndexOf('Ltr')
    $LabelIndex = $HeaderRow.IndexOf('Label')
    $FileSystemIndex = $HeaderRow.IndexOf('Fs')
    $TypeIndex = $HeaderRow.IndexOf('Type')
    $SizeIndex = $HeaderRow.IndexOf('Size')
    $StatusIndex = $HeaderRow.IndexOf('Status')
    $InfoIndex = $HeaderRow.IndexOf('Info')

    $Disk.Volumes = $VolumeArray | Select -Skip 1 | ForEach-Object {
        New-Object PSObject -Property @{
            Number = [int]$_.SubString($VolumeNumberIndex, 3).Trim();
            Letter = $_.SubString($LetterIndex, 3).Trim();
            Label = $_.SubString($StatusIndex, 11).Trim();
            FileSystem = $_.SubString($FileSystemIndex, 5).Trim();
            Type = $_.SubString($TypeIndex, 10).Trim();
            Size = Parse-SizeUnit $_.SubString($SizeIndex, 7).Trim();
            Status = $_.SubString($StatusIndex, 9).Trim();
            Info = $_.SubString($InfoIndex).Trim();
        }
    }

    $Disk
}