SimpleX Chat - a private and encrypted messenger without any user IDs (not even random ones)! Make a private connection via link / QR code to send messages and make calls.
SimpleX Chat is an instant messenger that is decentralized and doesn't depend on any unique identifiers such as phone numbers or usernames. Users of SimpleX Chat can scan a QR code or click an invite link to participate in group conversations.
-privacyguides.org
It's clearly proving to be the most innovative technology when it comes to decentralized communication, in my opinion.
In F-Droid, after disabling all anti-features, SimpleX still is listed. Signal never will be due to connecting to GCM or Firebase. Molly is an improvement for Signal but not for untrackable privacy like SimpleX from using a different ID with each individual SimpleX contact.
Not to mention, SMS was removed because it’s inherently insecure at every level. Keeping it would mean there’d be an insecure side channel into the protocol. While it’s a useful onboarding mechanism, it can also be abused — and was. So eventually it got removed to prefer privacy and security over convenience.