I'ld trust Signal, too.
Alas, I can't use it, because the app is only on Google Android and Apple iOS. Even their desktop client requires such a thingy.
Also, I like to get rid of #EvilTech dependencies, which includes AWS 🤷
Oh, and they still want my phone number. That's not necessarily a blocker for me, but … why?
Btw. https://proton.me/blog/is-signal-safe says Threema were #openSource, but AFAIK the server is not.