the good part of using a crypto is its not a country based but it some kind of a universal currency but first we need to give permision to a country if they will allow this kind of payment tool . setting a kind of payment system like this is also easy and wont need for other legal documents like what we do when we use common payment providers
Aren't you contradicting yourself here? First you claim that crypto isn't country based but some kind of a universal currency, but then state that we (who is "we"?) need to give permission to a country while you at the same time claim that legal documents aren't needed.
The usual way is that businesses accept crypto, then later find out what the legal consequences are as the legal system in most countries isn't up to date with the developments in the crypto space. In most countries there shouldn't be any serious consequences, but there are always countries such as Russia where things seem to operate in a different fashion in terms of legislation.
China can be added to the list as well, but at least they seem to be more direct with their approach, which can't be said about Russia. They have always followed through with sanctions and whatnot, which unfortunately didn't pan out well for crypto.
). Only I would suggest to have with you as many smaller bills as possible. When they are giving you change in their local currency expect to be cheated big time. 
