When I lived in Alberta, they used sand on the roads in the winter and not salt, so rust shouldn't be as bad as other provinces in theory. But yeah any Canadian truck undercarriage pics are a must. Getting a compliance letter for import to the US usually isn't a big deal [automaker says this Canadian vehicle meets all US regulations]. GM in particular I never had issues with, I brought down a GMC sierra that I got a deal on, and it took 48 hours for them to email a PDF letter I could show US Customs.
Although other automakers are getting really weird about it now, Stellantis/Jeep took forever, to get a letter for a Jeep JK we flipped. And Toyota isn't doing it with cars that are "too new" to prevent flipping.