We would not recommend crossing marketplaces, meaning if you are selling in Canada, only purchase from suppliers in Canada. If you are selling in the US, only purchase those products from suppliers in the US.
Amazon will not let you send in units cross-border, so it makes it much more of a hassle.
If you want to sell on both platforms, we recommend only using suppliers located in those marketplaces. Ex: US suppliers for US marketplace, and Canadian suppliers for Ca marketplace.
How would I ship from the US to Canada and vice versa?
Can Canadian supplier ship to the US?