Ability to stop/start/reinstall service workers, view app manifests, validate app manifests, add apps to the desktop etc, store local results as global variables in the console. Connect mobile devices and run a local server on the mobile device.
There are more, but I can't think of them currently.
The UI is not very pretty, but about:serviceworkers lets you reinstall or unregister serviceworkers.
yeah, i keep hearing that here on HN (and only here, for some reason) but i myself use firefox and chrome dev tools almost daily and i never once thought "yeah this is missing".
well, for one, chrome is actually missing one big thing for me: a dark theme.
Chrome dev tools have a dark theme. It's under settings.