I know Google Waterloo has some actual permanent engineering teams but Microsoft and Amazon Canada seem to be strictly L-1 visa farms.

The political climate is much talked about but if anything the rate of brain drain has increased as more and more SV companies make an effort to recruit in Toronto. In the early 2000s the subset of US companies that recruited at all in Canada did it strictly at UW. Now all the majors have a campus presence at even mid-tier Canadian schools like UVic.