If you want to find accounts from people in particular countries, one method is to search for the country's flag emoji. For example if you wanted to find accounts from Sweden, you might want to search for 🇸🇪
If you want to make your account searchable by country, you could add a flag emoji to your profile description.
(Obviously you have to be careful though, as sometimes flags are used by hateful extremist accounts, but normal people use flags just to indicate where they live.)
Yeah, some countries do have a really bad relationship with their flag, unfortunately. I guess this is going to vary a lot depending on where people live.