So, I’m self hosting basically this. I have a matrix server that is publicly accessible but I’m the only user on it. I’m also self hosting a handful of bridges, signal being one of them. I’ve played with the WhatsApp bridge, and I’m using an SMS/MMS bridge.
It’s basically a man in the middle for all your chat apps. The Signal bridge software will login to your signal account and have full access to everything. The bridge works by watching all the decrypted messages and posting them to a matrix room. The matrix room may or may not be encrypted. This means you need to put a lot of faith into the bridge code and the people hosting the matrix server. The SMS/MMS bridge I use doesn’t even support encrypted matrix rooms.
I personally would never use beeper. Even if I couldn’t selfhost, I would not trust one person/company with centralized access to all my messages. I’m sure they have good intentions and would never do anything to abuse their position but I won’t put anyone there.
You’re not going to like the pinephone, it just isn’t ready for you if you’re asking for notifications on your PC.
The calls are okay AT BEST. SMS/MMS have come a long way and should be okay. Battery life is MAYBE a day, if you’re lucky. Anything beyond that is painful unless you want to spend hours getting it to work with your own code.