DJI made the decision not to sell the Mavic 4 Pro in the U.S.., not the U.S. government. You can't buy what the manufacturer themselves has decided not to sell in any country, including in Canada, unless you buy gray market goods without any warranty.
Besides, there is a reason many Canadians have moved to the U.S., and it certainly isn't politics! It's the weather! Ever hear of the Canadian snowbirds? LOL! In Canada, half the year, you can neither play golf nor fly a drone in sunny weather.
While I, too, would have braved Canada over Viet Nam, it would never have been my forever home!