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.