Sub-page for each styleguide section / group / item

No idea where to start though...

We need to decide how the routes / paths should be like, and how to navigate between them.

Currently we have paths like '/admin/appearance/styleguide/' . $theme_name.
The navigation is using a secondary layer of tabs (local task links) below the primary tab "Styleguide".

How would a sub-navigation look like?

I have a module that does support this feature. It's not currently actively maintained but still working. It might be used for inspiration.

Flagging, as I am interested in picking this back up, time permitting.