SimpleX Chat is very secure. It is alway e2e encrypted, leaks less metadata than Signal, has enabled post quantum encryption, and has no user identifiers. It’s just not great with large group chats but they are working on solutions that should land later this year.

Can't speak for SimpleX but PGP is pretty good for privacy.

PGP or gnupg is still pretty good as far as I know. I don't think it was ever broken?