I think Greenland is part of Denmark.
Don’t forget administrative districts, like Guam, or Puerto Rico.
Tokyo has a “grid-based” street addressing system, that I never fully understood. There are streets with no name, there (wasn’t that a U2 song?).
I find that long/lat (don’t forget the Southern Hemisphere) is about the only universal constant. If I am writing software that has a focus on just one nation, that helps a lot, but I need to keep in mind, that I may want to expand it.
Normalizing time, across the International Date Line, or Prime Meridian, is also fun (Daylight Savings makes this fun. India has a time zone that has a 30-minute component).