The best GPU vector rendering library I have seen is https://sluglibrary.com/. The principal use case is fonts, but it appears that the underlying mechanism can be used for any vector graphics.
I think the issue with slug is that it requires a fair amount of pre-computation. So it's great for its use case: rendering glyphs, especially on surfaces in games.
I do something a bit like slug, but I'm sure slower, since slug is very optimized. (https://github.com/audulus/vger)