Implement SSE (Server Sent Events) as alternative to Google FCM for Push notifications

[MurzNN]

Here https://f-droid.org/ru/2018/09/03/replacing-gcm-in-tutanota.html is good article, describing SSE (Server Sent Events) as alternative to Google FCM for Push notifications.

Riot-Android F-Droid release miss push notifications and use long polling, that eats battery. Can we implement SSE (Server Sent Events) as alternative to Google FCM for Push notifications in F-Droid version of Riot-Android?

[MurzNN]

Seems Matrix protocol plans to add SSE support, looking at https://github.com/matrix-org/matrix-doc/issues/2024 and PR matrix-org/matrix-spec-proposals#2108