This project made me happy. You mentioned Flash as an inspiration. Have you looked at how Ruffle is handling vector art?

From what I recall they are converting it to triangles. Your solution (curves in the shaders?) seems both cheaper and more accurate, so I'm wondering if they could use it!

Ruffle is cool. From pixel inspecting the demo, it looks like they are using triangle fans with stencil & cover + MSAA, which was how I started!