How to add Firebase auth user to GCP IAM access policy

Question

I am creating folders in GCP Storage bucket for each Firebase Auth User my app has.

GCP allows to give folder level permissions in Storage, but is it possible to also add the access permission to a Firebase Auth user using the GCP IAM logic?

Answer 1

No, it's not possible. IAM doesn't know anything about Firebase Authentication users. When accessing objects directly from app where a user is authenticated with Firebase, you're supposed to use security rules to determine who can read and write those objects.