List external users across all sites and in what site groups they are

$m365Status = m365 status --output text

if ($m365Status -eq "Logged Out") {
  m365 login
}

Write-Host "Retrieving all sites and check external users..." -ForegroundColor Green

$sites = m365 spo site classic list -o json | ConvertFrom-Json
$siteCount = $sites.Count
$siteCounter = 0
$results = [System.Collections.ArrayList]::new()

$spoAccessToken = m365 util accesstoken get --resource sharepoint --new | ConvertFrom-Json

Write-Host "Processing $siteCount sites..."

foreach ($site in $sites) {
  $siteCounter++  
  Write-Host "$siteCounter/$siteCount - Get external users in site groups for $($site.Url)..." -ForegroundColor Green

  $response = Invoke-WebRequest -Uri "$($site.Url)/_api/web/siteusers?`$filter=IsShareByEmailGuestUser eq true&`$expand=Groups&`$select=Title,LoginName,Email,Groups/LoginName" -Method Get -Headers @{ Authorization = "Bearer $spoAccessToken"; Accept = "application/json;odata=nometadata" }
  $users = $response.Content | ConvertFrom-Json  

  foreach($user in $users.value) {
    foreach($group in $user.Groups) {
      $obj = [PSCustomObject][ordered]@{
          Title = $user.Title;
          Email = $user.Email;
          LoginName = $user.LoginName;
          Group = $group.LoginName;
      }
      $results.Add($obj) | Out-Null
    }
  }
}

Write-Host "Exporting list..." -ForegroundColor Green
$results | Export-Csv -Path "./cli-external-users-in-sitegroups.csv" -NoTypeInformation

Connect-PnPOnline "https://contoso-admin.sharepoint.com" -Interactive

Write-Host "Retrieving all sites and check external users..." -ForegroundColor Green

$sites = Get-PnPTenantSite
$siteCount = $sites.Count
$siteCounter = 0
$results = [System.Collections.ArrayList]::new()

Write-Host "Processing $siteCount sites..."

foreach($site in $sites) {
  $siteCounter++
  Write-Host "$siteCounter/$siteCount - Get external users in site groups for $($site.Url)..." -ForegroundColor Green
  
  Connect-PnPOnline -Url $site.Url -Interactive
    
  $users = (Invoke-PnPSPRestMethod -Method Get -Url "$($site.Url)/_api/web/siteusers?`$filter=IsShareByEmailGuestUser eq true&`$expand=Groups&`$select=Title,LoginName,Email,Groups/LoginName" -ContentType "application/json;odata=nometadata" -Raw -ErrorAction Ignore | ConvertFrom-Json)

  foreach($user in $users.value) {
    foreach($group in $user.Groups) {      
      $obj = [PSCustomObject][ordered]@{
          Title = $user.Title;
          Email = $user.Email;
          LoginName = $user.LoginName;
          Group = $group.LoginName;
      }
      $results.Add($obj) | Out-Null
    }
  }
}

Write-Host "Exporting list..." -ForegroundColor Green
$results | Export-Csv -Path "./pnp-external-users-in-sitegroups.csv" -NoTypeInformation