How does the macOS installer know the country it is in?

I bought a used Mac Mini from another country on Ebay. When I plugged it in the macOS installer listed my country (Portugal) and China as the topmost countries. How does it know this? And why China in addition to Portugal? Some more details: - The Mac mini didn't have any internet connectivity at that point, wired or wireless - I live in an isolated place so only my wifi networks were visible (internet and from a solar inverter) - I had plugged a cheap usb keyboard (in my local PT layout) - This happened twice as I had to return the first Mac mini due to it being the wrong model - Poking my Sequoia installation I can only find a wifi BSSID database in /System/Library/Frameworks/CoreLocation.framework/Versions/A/Support/factory.db which does not contain any information about my local wifi networks. - I had my iPhone close to me while setting this up, but tethering was not being used