Their terms state you can also be a non-US Resident Citizen (expat). But generally yes that service is only for US Persons.
I wasn't really making a point about privacy.com specifically my comment was more to imply there are services that allow for arbitrary billing addresses.
Debit / credit cards always show country where card is issued. By now you literally can't get card from a country you are not reside in. I guess there are few prepaid card exceptions, but they're generally rarely accepted anywhere. Banning those on e.g Stripe is super easy and a lot of SaaS do it.
I not saying it's impossible to bypass these checks, but you either have to be very tech-savvy person to do it right or you you even have to break the law.
