Not sure what you mean by "US address" in quotes. I have a Canadian bank account (with a Canadian address attached - not mine, and I declared that to the bank) with a debit card issued against it and that worked, as it should. I couldn't get a Canadian cc without residency even though the bank account has a Canadian address on it.
BTW I also found out that Canadian shops don't issue store debit cards - only store credit cards.
Slight correction. US, Canadian or Mexican credit or Visa/MasterCard associated debit cards, which have a US, Canadian or Mexican mailing address. And if a friend purchases points for you, a trap is that there is a limit to the number of points abled to be transferred. A friend can't purchase points with their US card and your Alaska Miles number.
Just wondering why you say this as I believe members have had friend's purchase miles for other member's accounts, and haven't used the gifting method that would equally works as well.