I used to demonstrate Stirling engines at outdoor exhibitions. Providing a heated surface was problematic so I used those freezable gel packs that are sold for use in picnic coolers. I had considered painting the top plate of the displacement chamber black to absorb sunlight and thus increase the top-to-bottom heat differential and consequent engine speed but I hate painting. Instead, I had some thin black rubber sheeting; I cut a piece to fit on the top plate and that worked well to speed things.

Stirling engines are sold commercially to power fans placed on top of wood stoves used for heating; they help to circulate the heated air...

https://www.stirlingengine.com/produ...ine-stove-fan/

A (possibly apocryphal) story I've heard is that small Stirling engines driving tiny generators were used to power radios dropped to French guerrilla fighters during WWII. Battery technology was weak and the engines could be run in a campfire while the fighters hid out in the woods.