Cause: Noob me released an app a few years ago without realising that I had set a far away location for my Firestore bucket. I can't change the location of the Firestore bucket once set, as warned here
Requirement: I need to change the Firebase project my released app uses.
Problem:
- I can't change the package name or signing key for the app I have already released on Play Store - as per here, i.e. I am stuck with my package-SHA pair unless I want to put a new listing on Play store
- The firebase project my app uses is decided at build time via the google-services.json file.
- I can't have the same package-SHA pair registered to multiple firebase projects at a time - as per here.
All this means that I can only have one release build working at a time - either the one that points to the old project or one that points to the new project. And since this is a mobile app, the adoption of any new release by users takes time.
What could be an approach to migrate my users without my app's earlier version just dropping dead when I switch the SHA keys? It will drop dead because Firebase Auth needs the SHA keys to be registered.