I mean, say, you want a really nice camera, or a drone, or maybe a gaming laptop, and since those things are made in China, they are too expensive to buy right now in the US, since tariffs are over 100%. So you just go to Canada, buy the thing, unpack it from the packaging, and pretend like its just personal items. Just like a smartphone.
AFIAK, border agents usually don’t ask if you bought your phone in the US or from outside, they shouldn’t ask about other personal electronics, right?
If you walk over the border, or use another form of transport (plane, bus or taxi), then return in a car. Yes, you’re importing at that point.