So, I have a Threema license, but from what I’ve seen its encryption isn’t post-quantum. Signal’s encryption seems the strongest. I host my own matrix server.
Also, I kind of don’t care where the servers are or which provider it is. Everything is encrypted anyway.
I just saw your reply to me and was about to say the same thing, but they worded it perfectly. And I did mention metadata as a key point in my original post.