But if you officially operate somewhere, they can sue you, I thought that was common knowledge?

Anyway, not complying with local laws and operating in the country can get you in some serious trouble. And the trouble will escalate until you comply or pull out of the country.

Kim Jong Un can sue anyone. Like, they can sue Signal if they want. Sure, they have no way to enforce it, but they can sue (and win the case). It’s not like this would be a first, that happened quite a few times. Especially in dictatorship.