How do I use Google Firebase authentication for log-in in Nextcloud?


I’m working on web + mobile app where I use Google Firebase Authentication. So far, I only authenticate users with the Firebase Authentication Java SDK in my Java backend. There, the SDK also validates the Firebase Authentication token which is the result of the log-in. According to the Firebase Authentication docs, the identification token is an OpenID token.

Now I want my instance of Nextcloud to use Firebase Authentication for log-in. Is there an app for that? Or could I use the existing authentication apps for OAuth or OpenID?