@JulianOliver
Why the obsession with #Signal, Julian?
That's quite a list there, and each item represents a frustration with signal messenger over the years, and for me, ultimately all but abandoning it.
As a friend started a response to Moxie at his #36C3 talk; "You said so many things I disagree with, it's tough to pick a question"...
Abandoning all hope for signal, I have for a time now, been trying to keep some hope alive for #SimpleX Chat. The protocol idea is excellent. The current implementation not so much, and I am not sure yet what to make of the direction in which it would seem that the developer wants to push it. There may be political motivations there, other than simply creating a messaging system.
That said, Simplex seems to have got a lot of stuff right, (ticks all the boxes on your list) whereas everything else, very much including signal, so far, has got wrong.
BTW, I've been at this game now FAR too long to suggest trying to move all your contacts on to yet another system, (you also, I imagine) so that's not the point here at all. Interested what you might think of Simplex all the same.