Status of the "Android Integration" app

it feels like we might as well have the current system of just letting Bangle.js itself do an HTTP request?

Yes, sure, that will be enough, especially for the beginning. If the notification generating process is not on a server, one can always use ntfy, with "just" http requests/websocket. What you can do with Bangle/the app though is to make sure it supports long polling/make that easy to access. It will be a bit more of a strain on the users data limit/phone battery ofc. I can always think about integrating the better version with Firebase, which should use less additional data/battery since your phone has already a connection to firebase.