Not a feature per se, but being in the process of building a PWA for iOS with access to the camera, the fact that the authorization dialog pops up every time the app is opened (meaning that the permission is not saved even if the PWA has not been modified) looks like a deliberate attempt to make this technology not truly viable, because it really provides terrible UX.
That "workaround" is only available for store apps, not PWAs. Apple would love if every web developer had to submit to their app store just to add features like geolocation and camera and notifications. And that's exactly what happens today.
