I was considering this myself, as many places around the world will be getting mmWave and I'll go travelling as soon as possible. Would be nice to have faster 5G.
According to the CBSA calculator, there isn't any duty on a phone Mace outside of North America. Some websites say there's a 8.5% duty rate, but I'll go with the CBSA. I use crossborderpickups.ca; I think it'll be only $10 to bring it over.
We'd still have to pay sales tax; 13% in my province, and that would be on top of any US sales taxes, which would make it more expensive than buying locally. Is there any way we can buy it online and not pay US sales tax?
I quickly googled to see if we have mmWave and came across an article that said Canada has the second fastest 5g in the world, but no mmWave yet as they're still sorting out who gets the frequencies. Given that I change phones every year, and the state of mmWave in Canada and the rest of the world, I'm not sure if I should I even bother with the logistics of getting it from the US.