Android actually does have this feature (I didn't know it either before today). Camera Switches via the Accessibility Suite is widely available since 30 September 2021 as mentioned on this page.
As stated here:
Camera Switches is a new Android accessibility feature that makes it possible to navigate a smartphone using eye movements and facial gestures. It uses the front camera as a switch to set up one action to scan and another to select an item.
Choose a combination of two facial gestures such as looking in a specific direction, smiling, raising your eyebrows or opening your mouth.
Here is how to set it up
Once you have the app, you can start setting up facial gestures. Here’s how:
- Go to Settings > Accessibility > Switch Access.
- Turn on Switch Access, then tap Allow to grant it permissions.
- Go back to Settings and select Camera Switch.
- Select Two switches (recommended) to set up two gestures.
- On the next screen, choose your scanning mode. Linear scanning moves through items one at a time. Let’s select that one.
- Now select two gestures from a list. One to scan and one to select.
- Go to Settings > Accessibility > Switch Access > Settings to customize your gestures, set up gestures for global actions and more.
- Now you can use gestures to navigate your phone. An icon at the top of your screen lets you know when Camera Switches are active.
There is also Project Activate. As mentioned here:
Project Activate, a new Android application, lets people use these same facial gestures to quickly activate customized actions with a single gesture — like speaking a preset phrase, sending a text, making a phone call or playing audio.
But it is not, for now, available worldwide:
Project Activate is available in the U.S., U.K., Canada, and Australia in English
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