When you plug an Android phone into a PC, you have the option to change the USB mode between file transfer/Android Auto (MTP), USB tethering (NCM), MIDI, or PTP. In Android 14, however, a new option can appear in USB Preferences: USB webcam. Selecting this option switches the USB mode to UVC (USB Video Class), provided the device supports it, turning your Android device into a standard USB webcam that other devices will recognize, including Windows, macOS, and Linux PCs, and possibly even other Android devices.
Webcam support in Android 14 is not enabled out of the box, however. In order to enable it, four things are required: a Linux kernel config needs to be enabled, the UVC device needs to be configured, the USB HAL needs to be updated, and a new system app needs to be preloaded.
iOS recently introduced this feature as well, and it makes a ton of sense for Android to go down the same path.