You can use Molly, a fork of Signal for android. It offers an alternative for push notifications.

I was for a while. Hosted a LOT of stuff on an i5-4690K overclocked to hell and back. It did its job great until I replaced it.

Now my servers don’t lag anymore.

EDIT: CPU usage was almost always at max. I was just redlining that thing for ~3 years. Cooling was a beefy Noctua air cooler so it stayed at ~60 C. An absolute power house.