I'm undecided on if Canada having nukes would be good or bad.

You're right that the more people that have them, the more likely someone will use them, which would be extremely bad.

But if the choices were: 1) USA invades Canada, 50,000-2,000,000 Canadians die (plus some number of Americans). 2) Canada has nukes, USA does not invade, no one dies.

How can you balance the existential danger of another country having nukes against so many deaths?

(All potential deaths, yes. But we're already solidly in theoretical territory. I sure can't accurately estimate the chances of the US invading Canada in all potential scenarios, nor can I estimate how much more likely Nuclear Armageddon is if one more country has nukes)