No politician in Canada has the stomach to do this - it would be incredibly easy to just say "fuck you and your tariffs, we're ditching the USMCA, making a new set of bilateral agreements with China and Mexico and giving free reign to entrepreneurs to jailbreak the closed ecosystem of tech", but the risk of seeing their support from US subsidiaries impacting political careers takes any steel from backbones away.

Shutting off the oil supply to US refineries would supplement the economic pain - bilateral agreements with China and India supplanting US and illegal Russian supplies would be a boon for Canada.

Cut out the US and see how quickly the world changes.