Sure, but if the threatened tariffs come in, that nearby market will drop considerably. The EU is also a bigger market than the US. 440mil vs. 340mil.
Usually when evaluating markets you consider how much money the relevant participants have, not just how many of them are.
For example China has 1bn+ people, but Canada probably shouldn't sign a free trade deal with them.
Considering how tightly Canada is currently coupled to the US, this would be an absolute nightmare for many businesses. Yeah you'd gain a hypothetical overseas market, but in turn you're losing alignment with an absolutely massive market right next door! That's something like 60% of your import/export, gone.