Currently, if we use this type of routing, I have noticed at least the nav-side-bar contents and links get broken, but probably some other things will too.
I've looked at the same thing, to allow hosting examples in iframes (so an empty root layout, with the layout for docs within a (docs) group). Haven't got to the stage of making it work yet.
My use case is to get different layouts, without nesting pages: e.g. this can give me docs/ in water layout and docs/admin in fire layout
Currently, if we use this type of routing, I have noticed at least the nav-side-bar contents and links get broken, but probably some other things will too.