With android you must create app in firebase and write all app info,then connect with your project,
you can read this in documentation:::
If you have not already created a Firebase project for your app, do so now by clicking on Add project in the Firebase Console.
In your new project console, click Add Firebase to your Android app and follow the setup steps. Make sure that the Android package name you enter is the same as the value of
android.package in your app.json.
google-services.json file and place it in your Expo app’s root directory.
In your app.json, add an
android.googleServicesFile field with the relative path to the
google-services.json file you just downloaded. If you placed it in the root directory, this will probably look like
Finally, make a new build of your app by running
expo build:android .