I've heard and read recently about a warrant that shows that the US government is monitoring push notifications on iOS and Android. This is possible because push notifications mostly work remotely, using "push notification post office" servers at Apple and Google.
I am aware that certain apps; such as Threema, Signal, Proton, Tuta, and others; use their own servers for push, but not all apps will do this. So, as a deGoogled operating system, how exactly does LineageOS handle push notifications?
Some apps such as Signal implement their own push implementations that you can opt to use and they usually suck; unreliable, huge battery drain or both.
Some apps implement support for Unified push which works great IME.
Most apps rely on Google though and it sucks. Some of the risk can be mitigated by using µG rather than the regular Google surveillance services on your device. Push notifications work rather well but it's not without compromise in other areas.