Firebase Cloud Messaging (FCM)

Minimum viable example

import messaging from "@react-native-firebase/messaging";

const status = await messaging().requestPermission();
if (status === messaging.AuthorizationStatus.AUTHORIZED) {
  const token = await messaging().getToken();
  // store token against user.uid in Firestore, prune on send failures
}

Plus an APNs key uploaded to Firebase Console for iOS. Everything else (topics, rich notifications, background handlers) builds on this.

1. Provider setup

iOS (APNs)