Feature detection first
The site checks for mediaDevices, getGamepads, PointerEvent, requestFullscreen and setSinkId rather than assuming support from a browser name. A feature can be Supported, Partially Supported, Not Supported or Permission Required.
Desktop
Current Chrome and Edge generally expose the broadest combination of media, gamepad and audio-output APIs. Firefox and Safari support the core input and media features but can differ in output selection, permission queries, gamepad mapping and fullscreen behavior.
Mobile
Chrome Android, Samsung Internet and Safari on iOS support many core checks, but system gestures, browser chrome, autoplay rules and camera selection differ. Touch-only devices are directed to touchscreen tools rather than mouse assumptions.
When a feature is missing
Update the browser, confirm HTTPS, check permission and operating-system privacy, then try another current browser. Unsupported features remain explained instead of being silently hidden.