I am a tenderfoot in the mobile app dev world myself.
This blog sums up alot of what it does:
The current implementation that @chamath has included in his build allow for analytics and the ability to send custom push notifications.
If you wanted to have an idea of how many users downloaded the app, or say you wanted everyone who had downloaded the app to get a notification on their cell phone of any important updates or milestones, you would be able to do so from the Firebase console.
All that is needed is a Gmail account to create the google-services.json.
Well, you also need a name for the app. Something like org.flarum.discuss
Here is a view of my own Firebase console. Keep in mind, I have only a handful of users and data only represents my own tests of running the app on my phone.
Its my opinion that having an Official Flarum Discuss App on the Google Play store could provide great analytic potential.