[codedokode]

Aren't open source apps like Jabber or Element which do not require a phone number and allow to host your own server, a much better playground?

[zaik]

Yes, and XMPP over Tor already seems to be popular on the dark web.

[bydlocoder]

It was the default method of contacting the dealers on Russian darknet when everything was a just a message board (hell, it was available without TOR) and not a proper marketplace