What's easier: to obtain state ID, or to sign up to a website with your preferred username and password?

Well, I and a lot of the people I'm going to talk to through things like Signal are going to have a state ID regardless as I live in a country where one practically needs to drive a car to function in society.

On top of that so many other things just inherently expect one to have a phone number. It would be somewhat odd to not have a phone number for most of the people I know and talk to through platforms like Signal.

So to your question of which is easier, having the state ID and a phone number is easier because I'll already have that for a multitude of reasons.

If you live in a place where its rare to have a phone number, then yes I agree Signal probably isn't a good choice.

Obtaining your first id is obviously difficult. But so is obtaining your first computer. If you’re on good terms with your government, obtaining the id is easier. That’s really the key. Sure if you focus on hostile states this stuff all makes sense. If you’re insistent on hiding from authorities then many things become much more difficult, by design.