Usually the fuel cap is on the passenger side according to the country of origin, so for example European = right side, Japanese = left side. It’s not 100% bullet proof but it can eliminate a bit of the guess work if the car doesn’t have an arrow to indicate such side the cap is on.
Denmark to US. I did walkman and cassette deck repairs before Covid. It was possible to earn a pretty penny by buying broken decks on eBay, fixing them, and then reselling them.