No additional scopes are required to make this example work. I believe App Engine instances already have the required cloud-platform scope.

I don’t think Firebase Auth can be integrated with the oauth_required decorator. But there’s a way to authenticate users with Firebase Auth in an App Engine app: https://cloud.google.com/appengine/docs/standard/python/authenticating-users-firebase-appengine

This essentially handles the authentication client-side, and then sends the user’s ID token to the server for verification.