How could anybody even determine that? What a nonsense question. Everybody had a stake in it, and Canadians were part of the UK with a vested interest in defending Britain/Scotland & Ireland. Those from Quebec probably had a vested interest in protecting their homeland of France as well.
Americans of all kinds are pretty scrappy in a fight--and even though it wasn't ever right for Europeans to colonize and steal the Americas, they developed some mad skills in roughing it and being resourceful in order to expand westward over the centuries. An attack on Pearl Harbor in combination with the invasion/attacks on our World War One allies was enough to make any North American go batshit crazy with a desire for revenge. Even Americans of German heritage like my grandfather, fought like Hell against the Axis powers. He was greatly disappointed and disturbed by his father's and grandparent's homeland and wanted to kick some real authentic Nazi ****. This would certainly be how most Italian and Japanese (yes, even Japanese) Americans felt as well. A lot of Americans in Canada and the US, of course, came or had family who came from most of the countries being attacked by the Nazis, so of course they're going to be angry beyond words. Native Americans and African Americans pitched in too, by choice not just by draft. If you have attacks against Jews, by people who only like Aryans, then who comes next after Hitler finishes off the Jews, Poles and Communists?