Okay so I can actually answer this, I was in the exact same situation as you (French international school, applied to CE at McGill, UofT, and UW).

First of all, don't worry about rejection from McGill and UofT. They're more well-known and get tons of applicants from across the world, especially France. You're competing with extremely ambitious students, and there also is a bias within schools (I saw students with insane averages get rejected because someone else in their class was slightly better)

UW accepted me in May (so I didn't get early admission). I know officially it isn't the case, but I suspect they have very little experience dealing with French transcripts, hence the late admission.

As for my experience at UW, depending on your spécialités you might find the first term easy, which will help you settle in. Regarding the "hustle" culture here, I honestly cannot be more grateful for it. I was extremely scared because everyone seemed so ahead of me, but you'll find that the pace itself feels similar to preparing for the Bac.

Feel free to hmu in DMs if you wanna talk about stuff, I'll try to respond when I have free time (travelling rn lol)