I don't even know how Europe would respond to that, and I live in Berlin.
Canada… not so much. For all the talk, he'd be absolutely screwed if he tried. If you think Fentanyl is a problem now, wait until it's supplied for free by drones sent by Canadian civilians paying for it out of pocket because they've never heard of the Geneva Convention or the Chemical Weapons Convention.
(Harder done than said, of course; if it was that easy to mess with populations, western Russia would be high as a kite right now).