I'm angry!

chown.ps1

param(
    [string]$RootDir,

    [switch]$DryRun
)

# $currentUser = [System.Security.Principal.WindowsIdentity]::GetCurrent()
# $currentUserName = $currentUser.Name
# $currentUserSID = $currentUser.User.Value

$currentUserName = $env:USER
# $currentUserSID = & whoami /user # need to extract the value manually!

function Scan-Dir() {
    param(
        [IO.DirectoryInfo]$Dir
    )

    $items = Get-ChildItem $Dir
    foreach ($item in $items) {
        $acl = [IO.FileSystemAclExtensions]::GetAccessControl($item)
        $owner = $acl.Owner
        if ($owner -ieq $currentUserName) {
            # Write-Host "Already $owner : $($item.FullName)"
            continue
        }
        else {
            Write-Host "Taking from $owner : $($item.FullName)"

            if (-not $DryRun) {
                & icacls.exe $item.FullName /setowner $currentUserName
                & icacls.exe $item.FullName /grant "$currentUserName:F"
            }
        }

        if ($item.Attributes.HasFlag([IO.FileAttributes]::Directory)) {
            Scan-Dir -Dir $item
        }
    }
}

Scan-Dir -Dir (Get-Item $RootDir)

Alternative: Add a new local group, add AAD user into the group, apply perms on the group.

net localgroup GroupName /add
net localgroup GroupName Domain\Name /add

From https://superuser.com/questions/1016528/how-to-give-file-permissions-to-azuread-user-on-windows-10