You may be missing my point. If no one believes in the country’s existence, including the people who live in the land that the country is purported to encompass, then it doesn’t exist. Nations aren’t tangible physical objects. They exist in the collective human imagination. Yes. Your passport is just a notebook if no one believes in the country it is supposed to be for.

Sealand would be of note here. This is basically that exact scenario. Dude buys an old oil platform, calls it a country and issues a bunch of passports. Debates abound over whether they should be accepted or not.