In addition to SimpleX, I recommend Molly, a hardened fork of Signal...over Signal.

nostr:npub1h0uj825jgcr9lzxyp37ehasuenq070707pj63je07n8mkcsg3u0qnsrwx8 ... looks interesting. I know it's still way early and expensive, but will you seek to have your implementation of Signal's protocol independently audited?

Also, are you open source? Do you have an open Git page to check out your code?

Thx