@mgilang Someone with extensive Firebase experience might be able to show how to add that.
The issue is that this android app just emulates your flarum website in an android window.
Its not a native android app.
Someone would need to find a way to replace / migrate the current mysql authentication with a firebase authentication. There is some documentation online about how to do this but its way over my current dev abilities.
Ref:
http://marcelpociot.de/blog/2016-06-20-synchronise-laravel-eloquent-models-with-firebase
https://github.com/mpociot/laravel-firebase-sync
https://stackoverflow.com/questions/38425743/migrate-mysql-to-firebase
https://db-engines.com/en/system/Firebase+Realtime+Database%3BMySQL%3BSQLite