Looks pretty cool. Some comments on usability, It would be handy to see a visual indicator of which capabilities where missing from each browser - maybe you could colour each section heading Green or Red? It would also be handy if you could toggle all open/closed.
> It would also be handy if you could toggle all open/closed.
Added, thanks! I really like the suggestion to use some kind of indicator in category headings, too.
It might not be the objective of the owner of that site, but what I'd really like is an updated/maintained subset of what PWA features/components are usable across a selection of browsers - like iOS Safari and stock Android Chrome, Or Chrome/Safari/Firefox on desktop (perhaps filterable by OS too)?