GetAzureAppProxyApplications.ps1

$apps = Get-AzureADApplication -All $true
foreach ($a in $apps) {
   try {
      $appProxy = Get-AzureADApplicationProxyApplication -ObjectID $a.ObjectID
      Write-Host "App Proxy config found for $($a.DisplayName): $($appProxy.ExternalURL) using $($appProxy.externalAuthenticationType)."
   } catch {
      #no app proxy config found for the app
   }
}