Android has long had an Accessibility API that's intended for developers to build apps and experiences aimed at helping persons with disabilities, though it isn't always used for that purpose. Google intends for apps that use the Accessibility API to fall into a few categories, including screen readers, switch-based input systems, and voice-based input systems. The company's very own "Android Accessibility Suite" app provides, as its name implies, a suite of accessibility tools so persons with disabilities can access their device. The latest update to the Android Accessibility Suite adds a new way for users to control their devices: "Camera Switches."
Beta version 12.0.0 of the Android Accessibility Suite app was included as part of the fourth Android 12 beta release, which rolled out to Pixel phones a few days ago. The updated app brings "Camera Switches" to Switch Access, one of the accessibility services included in the Android Accessibility Suite app. Switch Access contains tools to let you interact with your Android device without using the touchscreen. With Switch Access, you can connect an external device via USB or Bluetooth to select items, scroll, type, and more. Now, you can use "Camera Switches" to control your device with nothing but your own face.
Camera Switches currently supports setting a handful of gestures to a handful of controls, though it's possible the list may grow in the future. You can, for example, have the app detect when you open your mouth and then map that to open the notifications panel. You can also have it check for when you raise your eyebrows and then have the phone return to the home screen.
When the Camera Switches feature is active, a persistent notification icon is shown to tell you that your camera is actively being used. Android 12 shows a status bar indicator whenever your device's camera is being used, so this notification icon may seem redundant. However, the updated version of the Android Accessibility Suite app doesn't seem to be exclusive to Android 12 devices as we were able to sideload the APK to get the new Camera Switches feature on an Android 11 device. Since it seems that the updated release isn't yet rolling out for users on Google Play, you'll either have to wait for the update to begin rolling out or sideload the APK from a site like APKMirror.