I'm pretty sure the OP has figured this out, but in case anyone else stumbles upon this thread trying to solve the same issue, I wanted to give my input.
Like the OP, I also had an unlocked international model, in fact, I'm on my second consecutive such model. I had an unlocked S7 edge from Singapore and now I have an unlocked S9+ from Hong Kong. I have successfully set both those up for use in Canada with Samsung Pay without ever having been used for a second anywhere else.
I believe the whole point of an "unlocked" phone is that it's NOT region-locked, where you need to use it for 5 minutes in the home region before "exporting" it elsewhere.
The only thing you will not get is the Canadian offers within the Samsung Pay app. You will see the offers from the market that the phone was intended for. I only see offers meant for Hong Kong, but hey, I can live with that in exchange for getting the features I wanted in a phone.