You can install your own precompiled Android, make shure the reciever does aswell, host an end-to-end encypted messaging server on your own and you are set. Maybe use thor browser aswell, but that shouldnt be necessary
No but seriously the “spy on the other users phone” is something you got a point about. But isnt that a genuine issue if you use non-open source code on your phone? Like if you go that far isnt anything other than stock android that you compiled yourself unsafe?
You can install your own precompiled Android, make shure the reciever does aswell, host an end-to-end encypted messaging server on your own and you are set. Maybe use thor browser aswell, but that shouldnt be necessary