There's Beeper and bridges like Heisenbridge which could do this work but the crucial question here is why? The frontends you're talking about help to obscure you from sites on the open web; there's not going to be much of a benefit to adding another party into your chats, which are linked to your phone number.
Two things can simultaneously be true, Daniel can be an individual who engages in very problematic behaviours and GrapheneOS can still be the most-secure and reliable OS out there.
What is the point of posting something from 2015?