and requires phone numbers (meaning your real identity in the US).

This gets shared a lot as a major concern for all services requiring a phone number. It is definitely true that by definition, a phone number is linked to a person’s identity, but in the case of signal, no other information can be derived from it. When the US government requests data for that phone number from Signal, like they occasionally do, the only information Signal provides them with is whether they do have a signal account and when they registered it last and when they last signed in. How is that truly problematic? For all other services which require a phone number, you would have much more information which is where it is truly problematic, say social graph, text messages, media, locations, devices etc. But none of that is accessible by Signal. So literally the only thing signal can say is whether the person has an account, that’s about it. What’s the big deal about it? Clearly the US government already has your phone number because they need it to make the request for Signal, but they gain absolutely no other information.