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?
According to the customs and border protection website, there is a max limit of $200 that is free from duty and tax if you’ve spent at least 48 hours there, and it has to be for personal/household use. There are amount limits on alcohol and tobacco.
But if it’s something like a single phone, you pay in cash and open it there and dispose of the packing material. You could get away with violating those restrictions, but at your own risk.
Side-note: The limit is $800 if you go to the Caribbean, and up to $1600 for places like US Virgin Islands
Why is there any sort of limit at the US Virgin Islands? It’s a US territory, you don’t even go through customs.