In the US, at least, all egg products must be pasteurized
The term “egg products” refers to eggs that have been removed from their shells for processing at facilities called breaker plants. Egg products include whole eggs, whites, yolks and various blends with or without non-egg ingredients. They may be available in liquid, frozen, and dried forms (eggs inside their shell are NOT egg products.)
It would seem to be the same in Canada though that link is less explicit about the requirement. As such, I don’t think you’ll be able to find unpasteurized egg whites legally sold commercially.
As stated in an answer to the question I linked in a comment:
With a lot of whipping (and more cream of tartar or other stabilizers) pasteurized egg whites (whether from pasteurized eggs or from cartons) can make meringue though it most likely won't be as stiff as those from non-pasteurized eggs
But as this answer to a different question mentions, it can make life more difficult than unpasteurized egg whites due to the nature of how egg foams work & pasteurization works.
You are unlikely to be able to buy unpasteurized egg whites, and for best results will want to crack your own eggs, even if it means you have to figure out something to do with the yolks (pasta, perhaps?), but you should be able to get by with a bit of extra care and effort using pasteurized egg whites.