I have Facebook and Google authentication working fine:
Recently I added also Play Games (this is configured and working fine in my app) but I can't find how to sign in using this. Some articles have Google's code to singing and the only reference I found is this, but not Flutter related: https://firebase.google.com/docs/auth/android/play-games
There is also this package, but it's not really used: https://pub.dev/packages/game_services_firebase_auth
Is that package the only way?