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?
I live a few miles from the border and cross at least weekly. You could generally get away with this for a handful of things, especially if you’re smart about it (dispose of all packaging and tags, have an otherwise legit reason for a short visit, etc).
But if they question you, and they determine you’re intentionally lying about it, you can expect to pay additional fines and lose several hours of your life.