Comment by hagbard_c

They won't scan my messages since I run my own XMPP server and clients using only free software - prosody for the server, Conversations/dino/gajim/converse.js for the clients. OMEMO (the encryption scheme used by 'modern' XMPP systems) uses the same double-ratchet encryption as Signal without the dependency on a central Signal server.

Prosody can run on just about anything and is mostly maintenance-free, give it a try I'd say. You'll want to get a domain for it but that's easy and cheap.