Hi! Glad you like it!
Yeah it's pretty much GLSL with maybe some small differences. For learning that i recommend the book of shaders. Also take a look at this video, it's a bit older but holds up pretty well. If you understand the idea behind shaders it should be pretty easy to convert to godot using this guide.
I do want to add more stuff to the generator at some point. Those are good suggestions, but don't want to riddle it with too many options. I like the polar jet idea, might be coming at some point. And if you make some cool shaders I'll definitely consider adding them!