Yup. It's not ideal, but it generates heat without electricity and it's safer than heated blankets or other options.

Poke some holes in a large tupperware, line it with a towel, and concentrate the heat on one side so the dude can move around to thermoregulate.

Beardies and geckos are a bit different, you may want to reach out to others with geckos, but that's always been our back up plan with our dude.