Meanwhile I've switched my family and friend to Signal with great success.
I've been trying to find a solution to bridge rooms across chats to make the change simpler for anyone, and matterbridge[^1] does a lovely job - except for Signal.
Moxie made it stupidly hard to connect to Signal with anything that's not the official app, which is definitely a hostile act towards anyone who doesn't want to have the Signal app on their phone - the Signal desktop software needs the mobile app to work:
"To use the Signal desktop app, Signal must first be installed on your phone."
I definitely have my issues with Signal. That said, it's simple, and works reasonably well, it's just not a nice system at all from the dev/libre perspective.