It's too late now for the initial hand-on-the-hub heat test on yours, but when one of my calipers froze up and smoke came from the brake pads AND the wheel bearing grease AND the burning brake hose(!) you could still feel that the bearing hub was almost too hot to touch an hour and a half later.
Has your Bronco been sitting for extended periods? Lots of miles without verified maintenance? Could be either brakes or bearings, so time to handle both.
If you drive yours again you can test that theory, but using our experiences as your guide I'd not even drive it until you've pulled the wheel bearings apart and checked both brakes and bearings.
When it happened to me I was thinking it was some kind of wiring burning underneath because I could not see anything obvious and it smelled kind of strange. In the parking lot (big Bronco gathering for burgers) member BajaBronco touched the hub and without actually uttering the words, basically said "well there's your problem right there!" and that was that.
At that point we did not know if it was a brake or a bearing, but after pulling things apart it appeared to have started in the brakes. But the bearings needed replacing anyway because the grease in the back had charred and the seal melted and they showed signs of age and damage.
Does sound like the bearings had a hand in things as much as the brakes, but it didn't matter because I replaced all of the above anyway.
Paul
