Signal no longer requires a phone number. You can now create an account. Not sure if that helps your outlook on it, but yeah. It was a fairly recent update that this was rolled out.
Edit: being told we still do need numbers to register. I haven't gotten a new phone since well before the change was made, so I haven't actually created an account and gone through the process. It looks like I misinterpreted what was going on when I read the changelog.
This is why we can't have nice things😂