I wrote a program that has programmable brushes about ten years ago, it's a bit different from moss in that it has a physics simulation underneath rather than a sort of shader, but I've always thought this kind of approach has a lot of potential.

It feels _amazing_ to draw a bird in a single stroke!

Maybe this can give you some inspiration!

https://laura.fm/generative-art/wind/wind.html

Very cool. Side note, but I've always thought that a combination of a pixel art editor like Aseprite coupled "cellular sand sim" would be really cool.