I share your sentiments about Firebase being heavily under-utilized — it’s really magical what you can do without any or with very little back-end code (e.g. few Serverless functions).

What I am missing is a self-hosted / open alternative. I will be looking into Parse Server (https://parseplatform.org/) / Back4App (https://www.back4app.com/), but so far I prefer Firebase SDKs.

Power to the front-end!