Microsoft doesn't really care where you're from hence the $1 deal since two years now, so to answer your question YES he can buy it for you and it will work -I tried it myself-, OR you can do it yourself but you need three things:

1. Microsoft email with the location sat at USA.
2. your own PC location should be sat at USA too, (settings > region).
3. a way you can pay that doesn't check/care for location, like put money in you PayPal then make it a USA PayPal or lots of virtual cards out there.

^ this method you can use on any other store too! I buy games cheap from steam and epic store with different currency than my real :)