If I remember hearing correctly there is a piece of the drive train (maybe) that's super easy to remove and carry around. It apparently makes the truck unmovable. You'd need a crane or dozer.
Yes, I remember an American trucker demonstrating that on You Tube during the first Australian truck blockade. It was about a 16-inch metal rod that needed to be removed from under the front chassis.
If they have air brakes, and trucks generally do (or used to anyway), you can cut the air line and the brakes will lock. It’s a fail-safe design. If the brake line fails, you want it to fail in the stopping mode, not the “no brakes” mode.
Seems like that would be a pretty inexpensive way to make a truck very hard to move.