Nothing has changed wrt the personal exemption. Imports under $800 are exempt (i.e. you always had to pay tariffs on an expensive watch). I don't know how many commenters here actually realize it, but the de minimis exemption changes only apply to commercial import, which is how Temu and others could send a $10 piece of crap from China to your doorstep.

I don't know if the Swiss post office has realized this, but it's true.

Edit: one bit of nuance (see my comment downthread with some of the actual laws and the EO) is that if you buy a watch from Chrono24 or something then it's more like the Temu use-case, and I think the personal exemption probably doesn't apply? But if you go to Switzerland and pick up a $799 watch and post it back or carry it on a plane, then there's no problem.