I’m always skeptical of libre projects which present themselves as radical left projects like Riseup and Autistici which this seems somewhat similar to.
Not because I don’t neccesarily judge the devs intentions, but small collective projects don’t have the resources to stand up to intelligence agencies and other broad cyberattacks, and being seen as in solidarity with far-left activism puts a target on your head.
You and I can’t even use signal, unless you wanted to tell me your phone number, so its also useless as general-purpose online communication.
Usernames as secondary identifiers are being rolled out so this is no longer true.
“Usernames on Signal are optional. If you choose to create a username other Signal users will be able to find you by this username and contact you without knowing your phone number.” -Pointed out from dev commits on signal forum https://community.signalusers.org/t/signal-introducing-usernames/9157/3
I think that’s overly hopeful. Webrtc dependent sollutions can’t be reliably used over TOR and most major VPNs. Being self hostable is definitely a plus, but from the perspective of the communication protocols themselves Matrix is outclassed in both usability and call/message security.