@Capt-Codpiece Thanks so much for this guide, but you forgot to mention that you need to change your address in MS store to a US-based one, it's not enough to simply go to the US store. It also took me relogging and waiting around a little bit for it to update my microsoft account region to US from EU.
@Lokranas Hope the above helps you, it worked for me. Just make sure when you go to redeem the code it says United States instead of anything else for the country in parentheses. Make sure you relog after changing your region in the settings by altering your address, it's not enough to simply go to the US storefront, as noted above.