Here’s a lovely Design System that interestingly uses Eleventy for its reference website and other generated artefacts:
We use Eleventy for both the static documentation and the dynamically generated parts like component playgrounds and design tokens. We don’t currently use a JavaScript framework on the website, except Duet’s own components.
I find Duet interesting both from the Design System perspective (it contains lots of interesting component techniques and options) but also in terms of how far 11ty can be pushed.