Saw this today: buddy burners. In TLD terms, it could just be some tinder, cooking oil (or animal fat) and a can. Provides 8-10 hours of light, maybe, and a 1C warmth boost. I used to make these all the time as a kid!
https://www.rootsimple.com/2007/01/buddy-burner/
A variant uses two cans and can be a stove.
https://www.scouts.ca/resources/activity-finder/buddy-burner.html