Scoped bolt action hunting rifles because they make great impromptu Sniper rifles. Also, as a resistance fighter in asymmetrical warfare you're not going to beat an army with firepower and continuous engagements. You have to rely on hit and run tactics and rack up a body count over time that will make the occupation too pricey to keep up.

A compact, takedown/folding stock version is also preferable because it will make it easier to carry it in a non conspicuous bag in the city and blend in with the population. Trying to hide in the woods against an enemy with thermal vision and surveillance drone capabilities is a bad idea. The only way to hide human activity nowadays is among other human activity.

Although lately shotguns did find a new use in the battlefield against drones. But once again, they're long, hard to conceal and you're better off hiding among population.

Also, speaking of new tech, I think it is worth learning how to operate drones. It might have become the safer way to do things like that. They're easy to conceal and easy to deploy and operate out of sight. As a bare minimum it will force the invader to use high power radio jammers that are absolutely not healthy to stand around over a long period of time, further increasing the cost of the occupation.

A good idea.

Keep in mind that you, the people outside of the U.S., and even a solid majority of people within the U.S. are on the same side.

He only has about a 30% approval rating on any given thing. In the U.S. there are a lot of people who have been looking around waiting for someone to do something in order to feel comfortable acting, and if he attacks Canada the people in the U.S. will see that as there instantly being 30 million people who are willing to do something, and it might trigger an active resistance within the U.S..

By all means, get firearms licenses and training, but be ready for something much more insidious than troops coming across the border if the US takes things this direction. We are already infiltrated by political and militia movements that are aligned with the US, and our own security and intelligence forces are deeply integrated. Worse than that even, we are on a giant island with them, any allies that might come to our aid are an ocean away, and the US has the capacity to easily blockade our major ports and cut us off from trade with the world. The US is positioned to break our society down economically and socially, utterly empoverishing and dividing our populace before making any move at actually seizing control of government and calling us a state. This is what they do to destroy countries. They do it with sanctions elsewhere, but they have even more powerful tools than those to use against us because of our shared geography and integration. So, yes, get firearms training and arm yourself, but be ready for internal chaos and to push back against domestic movements to align and capitulate, not just little green men coming across a border. Also, think about how to support & collaborate with Americans who are trying to fight fascism domestically. They are the front line, and our best hope may be their civil war if the US goes this direction.

Instead our government is focusing on taking guns away from legal owners. The whole gun buyback program at the very least should have been paused once threats to our sovereignty started.