Hi,
It would be very helpful if a user could be automatically enrolled in an FCM topic when they log in to the PWA using a VAPID key.
Currently, when I generate the token at login, it's saved in the Firebase Realtime database in the /fcmTokens path. The problem is that this process is very data-intensive: the ESP8266 must read all the tokens in /fcmTokens and send notifications individually, resulting in a significant increase in handshaking, SSL, and device heap memory traffic. This would not happen if Firebase added topic subscriptions/unsubscriptions from PWAs.