Firebase and Firestore are not the same thing, Firestore is just one database option on Google Cloud. Firestore is quite good for a lot of apps that are primarily CRUD type experiences, and let’s face it a lot of apps are. If however you need to do complex analytics type queries you can replicate that data to one of those services for the purposes of those queries. ElasticSearch is a common choice especially if you require full text search and fuzzy matching functionality. Algolia is a third party serverless option that can work quite cheaply for small datasets but can become expensive for large volume. And there is also the ability to stream data directly from Firestore into BigQuery and keep everything within Google Cloud. With BigQuery you can use traditional SQL but it operates serverlessly and is charged based on data throughput. Far less hassle than managing a Postgres installation.