I don't think you get it...
US is really unprepared for a low intensity guerrilla warfare full of random attacks to create financial damage....
It is not a case could US take Canada and hold it, it is how much would it cost? The attacks on infrastructure and institutions would create havoc and have a huge security bill...
Look what IRA did in 1993 with 100 lb of Symtex (Czech C4) and a ton of fertilizer(enough for 25 acres)...
en.wikipedia.org
The person that was killed was a photographer who snuck through to get a picture robot bomb disposal.. That cost that bomb alone was £2bn today... That was just the damage from the bomb... That doesn't include the massive security bill which meant people having bags checked going into the City for months... The redundancy sites that had to be set up...
So how much money does MAGA think they are saving by invading Canada?