I have a decent Firebase SDK wrapper
It includes firebaseui so you can do social/phone/email logins, as well as the core SDK. It initialises a namespaced apps so that you can have multiple clients running in parallel without clashes (something that would come up in a collaborative environment like Observable otherwise).
It also has an adapter for the realtime databases “listen” we manages tearing down subscriptions and maps a database location to a generator so it works nicely with Observables dataflow when uses as the value of a cell.
There is also a port of some firebase-admin functionality in a different notebook
This allows verifying and minting JWT from Google Service Accounts. Not much use in a users browser but very useful if you run the browser in a privileged environment like Serverless Cells / Endpoint Services / Observable . I built a whole serverless Oauth 2.0 server notebook firebase and observable: Federated IndieAuth Server / Endpoint Services / Observable.
There is also a video and app building demo here Chat application with Firebase on Observable (Twitch) / Tom Larkworthy / Observable