It seems really cool but I’m a bit wary of it due to the crypto stuff.
My issue is effective impossibility to selfhost. XMPP, Simplex, even Matrix are very possible to run on your own, while a Session node would be insanely, arbitrarily expensive (requires around $1000 now, IIRC used to be more). A hobbyist like me and you would not want to pour this much into something they provide out of the goodness of their heart.
Seriously, if you have this much disposable money, you’d be better off running a few Tor nodes in various places).