I was going to ask if Slug can be used as a general vector renderer. Or does it assume limits on e.g. number of curves/paths per area that are typical of fonts?

Eric answered a similar question on the Discord channel saying Slug is suitable for generic vector graphics. He recommends checking out the demo at https://sluglibrary.com/ (you can cycle through the examples with the space bar).

I think it is limited to integral quadratic bezier curves, which is sufficient for text rendering. But general purpose vector graphics almost certainly want rational cubic bezier curves too.