I was just wondering the same, so for somebody stumbling upon this:
There is a plugin-like thing to convert SVGs to Godot shapes.
More interestingly maybe: It's made with something called EditorScript which are ... well ... scripts that are designed to be run from the Editor, not the game itself.
I currently use it to generatively create polygons which (upon running the script) get added to the scene, so I can still tweak them manually.