One of my earlier posts included a campfire, among other light source models.

After importing them into Godot I took advantage of the built in 3D particle emitter and some lighting nodes.

campfire godot scene tree
The campfire Godot node scene, composed of the mesh, particle emitter, and a light source

With a little bit of effort and some messing about with the particle emitter, I got some very basic looking fire that will work well for my use case. Below are a small video of the campfire and a torch.