Hmmm. I have occasionally thought about this. I don't think there is a uniquely Canadian style of beer, but there is possibly a very Canadian regional history or preference. I'm getting at some history here, rather than what's currently 'defining' if there is such a thing.
My suggestion is that stock ales and variations are pretty Canadian. No not invented here, but preferred here during a time when beer drinking was much a working class thing and thus driven by that community. I'm going entirely by personal experience with this. Going to the Brunny for a table full of beer glasses as a student; some variation of a stock ale, 50, maybe Export. Other working class bars (sorry taverns) in Ontario and Quebec, largely the same. It's probably a generational thing, because, obviously lagers started to get marketed as "not your father's beers" and as an aspiration to those same working class drinkers as a step up.
How Canadian can we claim it? Debatable as much of Northern Germany has it's Dortmunder class. Yes lagers, but built for the same purpose, audience and often surprisingly similar flavour profiles. I think we might be best to go back to the 70's and 80's reputation of Canadian beer v.s. US beer. There was always some sort of stupid pride that Canadians had stronger and more flavourful beer. Not entirely untrue, but it really had more to do with the US commercial brewers pushing lighter lagers as mainstream while we stuck with the old simple standbys.
My point is that there is a style that has run in our veins for several generations. I had an old family friend who worked in the mines. He used to always add salt to his beer, claiming "new American style beers don't taste right without it". He was referring to Molson Canadian. LOL
So, to circle back, would there be an award winning stock ale? deep breath
But maybe the hipster trends of drinking 50 or Black Label might reawaken the conversation.
Personally, I would nominate Northern Ale as a good candidate.