I saw this at one of my friends i have to get alola eggs from far away for the trade-distance medal.
Rename your buddy to your country name.
(for bigger countries like the US or China perhaps city name etc)
I have a list of over 100 friends, remembering who lives where gets harder and harder and making a second list for my friendlist is meh.
Postcards from gifts do help sometimes to determine who lives where (Asian friends are sooooo great in that) but it can still be done faster.
With this small adjustment people can see where i’m from if they want to focus on distance-trading with their local community. If more people do it, then efficiency for gifting will go up. All you then have to do is click on a friend and you’ll instantly see where he lives, no guesses via postcard, no remembering names, no making secondary lists.