here is the problem that we face.
We have LGA-YYZ flight however my SO has a EU passport and american(american naturalization certificate) but not US passport. Since the trip is this Sunday would she be able to board and enter Canada with her EU Passport(not eligible for visa waiver for Canada) and the naturalization certificate which proves that she is an American(albeit with no US passport). Afaik americans do not need visas to enter Canada.

Cannot find a single proof that this is possible but I could be wrong.