What I have at home is an RPi monitoring some status. The interesting properties of Firebase in this case are receiving notifications (aka GCM) and the use of the distributed "realtime" database. The question is how do the events get generated. Can a script running on the RPi send data to Firebase?

• "Firebase Notifications" are sent solely using the Firebase console web UI. Not adequate.
• "Firebase Messages" can be generated via an HTTP POST with an OAuth token; however this requires getting the registration tokens for each device that should receive, which doesn't seem practical.
• "Firebase Database" is a synchronized JSON store. There are many REST wrappers (Go, Python, or just curl) that seem appropriate for the RPi to generate data. Authentication rules are set in the database console. See https://firebase.google.com/docs/database/rest/start