When building a web app that implements a camera with the MediaStream and ImageCapture APIs, one major gap between the web-built camera and the native camera is that the volume rocker keys on a mobile device cannot be overridden to capture a photo like they are in most native camera apps.

It would be useful to provide the web app with the ability to detect volume button key presses and override them to perform a custom action in the web app. It would be understandable to limit this feature to PWAs installed to homescreen or in a fullscreen mode.