I doubt there are many cheering on Trump in his crusade against Canada (or in his defense of Russia), but they do take some comfort and pride in him acting like the tough guy they hoped he would be, similar to how they responded to the blow up with Zelensky.
But I think there is a chance that American sentiment, on the whole, could shift toward outright hostility for some allies and sympathy for Russia if things continue. There are millions of people living in US, some of them citizens, with very strong ties to Canada, Ukraine, Mexico and other countries Trump plans to antagonize. It’s not hard to imagine even just a few rogue actors striking back if they hold the US responsible for a missile attack or a recession, or whatever, back “home”.