you don't have to "befriend" them. you send a friend request because that defaults to a push notification for users with the discord app on their phone. Now, with signal, i don't use it so i don't know how initial chats start, or whatever. The discord one is 0-click because the PFP in the friend request is the payload delivered via PUSH.

And to someone else's point - they had to block the request on their end with a MITM to do the 1-click version on signal. No such MITM is needed with the friend request.

As an aside, one time i got doxxed hard in an IRC channel with several hundred active users. I had a suspicion of who it was, and i knew they lived in chicago. So i "accidentally" sent a link to "screenshot proof" that was hosted on one of my domains. there was 1 immediate click. instant. Chicago. "accidentally" because it looked like i pasted an email body.

Packed the real screenshot and a complaint to the ircadmin. they said "and so you dox them back?"

can't win for trying.