Firestore is great, especially as a cleaned up and more capable version of Datastore, but Firebases's influence on it as a successor to Firebase Realtime DB is

Firestore is great, especially as a cleaned up and more capable version of Datastore, but Firebases's influence on it as a successor to Firebase Realtime DB is showing in this complexity here. IMO, the easiest and most secure thing is to not do direct DB reads and writes from your client. Use a traditional client-server architecture and have your server talk to the DB. The times I do use the Firestore client library, it's only for reading and only for the realtime updates. My security rules disallow all writes.