Binding brakes, or something else?

Hi.

My Jimny has been sitting for a while, because I bought a land rover

Anyways, when I went for a drive the other day it started pulling to the left, and smelled burned from the front left side. I was just at a store close to home, so didn't drive far. Tried replacing the glide pins on the caliper, and the same today.
It passed MOT just before I parked it, and it had no such problems then. So I think I can leave wheel bearings out? They were new last year, and I have only driven the jimny about 500km since.

Could it be anything besides the caliper piston binding? I could push it back a bit, but that was a struggle.. When I put the wheel back on after replacing the glide pins, I tried spinning it. And it made a woosh woosh woosh sound.. What I mean is that something was touching something, but not all the time when the wheel span.

Took the wheel off after the drive after changing the glide pins. Caliper was really hot. The rim was hot, but the hub itself was not that hot.

Just checking if it could be anything but the caliper, before I buy a new one. I have new brake lines for the front as well, so should probably replace those while I am at it.

If not driven for some time the rear brakes might be binding due to the hand brake left on.

Yeah, but in this case it's the front left brake, not the rear.

Okay. Caliper piston may be seized. May not be working as it should.

Also check that the pads are free to slide in the hanger, not able to rattle about but able to move smoothly.

If you can push the piston back in the caliper without too much trouble it is probably the caliper slides.
With the piston shoved back you should be able to pull and push the caliper easily.
In my experience, there is no point trying to determine what side has the problem because if you only fix one side, the other will start to stick!
I would check the pistons and slides either side, if there is a problem strip off both front calipers, remove, clean and lubricate all 4 slides. If they are pretty bad you might need to take the caliper right off and wrestle it out with the caliper in a vise!
While you are in there make sure the pads are not stuck in the caliper carrier. If they have been sticking on the pads may have uneven wear or have overheated, crumbly friction material. Might be worth sticking a set of brake pads in while you are there.
It all sounds like more work than it actually is and I assume you enjoy working on cars given you have bought a landrover, LOL!