I picked up my Vision Pro a few days back in Buffalo. Funny enough, someone at the same table as me who was doing a demo / picking up a purchase was also from the GTA. And the store reps helping us mentioned how there has been high traffic from Canadian customers at their store since launch.
Anyway, your Canadian Apple ID will work as expected (for iCloud, but no access to App Store or TV+/Music/Arcade/etc). You will see previous iTunes purchases you've made though (TV/movies, but not the updated 3D version of them - for whichever ones do have 3D available).
I had an American Apple ID from the past that I used to sign into the App Store (Media & Purchases). I believe you can create a new Apple ID here (and choose United States for the country):
https://appleid.apple.com/account
While in Buffalo I purchased a $50 US Apple Store gift card so I could throw some credit onto the account (as I don't have an American credit card or PayPal account). FWIW, when I was first trying to subscribe to TV+, it would give an error that I didn't have a valid payment method on the account. But then the day after it worked fine.
The target circle member I hadn't tried myself. But it looks like you can sign up on their website, and they have the links for the 3 month promos there too:
Target Circle [credit to
@bb147 ] for sharing that.
EDIT: Just tried the target circle signup. Damn that was simple. Just email address and name to sign up. And then the redeem button immediately jumps you to the 3 month credit and also sends you an email with code to redeem 3 months free.
EDIT 2: I noticed you can first signup for Apple One to get a full month free, and then when that is near the end stack it with the 3 month promo from target circle.
Hope that's helpful!