Don't use signal, use session for private chats.
My Session ID - 0538b7c759d645409a20b25de3c76ebdc48cec7e341bd41d487c8a65ebfd91f260
Discussion
What's session?
It's the best alternative until nostr devs find out a way to provide reliable private messages through relay.
It routes all messages through tor network and you don't need a phone number to signup, like on signal.