Account specific firebase
We've got a number of apps which can be classified into about 3 categories. The user data for each category is very similar but between each category quite different. So we're thinking we should create 3 different firebases, one to store the data for each category of app. However we'd like to implement a common account system since our users may use individual apps from any or all of the 3 categories. So ideally the user creates an account once & then just logs in using that same account going forward on any of our apps.
Therefore my question is would it make sense to create a 4th firebase that only manages user accounts with the actual table data including permissions for any particular app (ie subscriptions, purchases, etc)? At that point could we use the authentication token that would be returned when the user logs in to this 4 firebase to make requests to any one of the 3 other firebases?