I love your interpretation of the theme! And it's just so chill to scribble around and watch the particles float away. I feel like this would be really fun to expand on: colors, different brushes with different particle effects, and as you've mentioned the ability to save images would be great! And I'd love just some super chill music playing while I scribbled away!
Anyway, whether you decide to expand on this or not, great work. It's quite a bit of fun to mess around in.