Android P will include support for Bluetooth HID, allowing certain devices to be used as a Bluetooth keyboard and mouse, as well as a revamped Material Design interface. The features expected on the operating system have leaked for past few months and the latest one hints that Android P might come with the ability to use your smartphone (with Android P) as a Bluetooth keyboard or mouse.
With this support, developers can use mobile devices running Android P to input information via Bluetooth.
A patch adding support for the Bluetooth HID was committed in 2016, but the functionality was disabled for future Android releases. Right now, the update doesn't add a lot in the way of features for the average user - and Google discourages regular people from installing it - but that will change as we get closer to release this fall. It was quite the breakthrough, but of course, seemingly never legitimized or supported by Google and the Android team. With this feature enabled, it will allow your phone to tell the device that your phone is connected to that your phone is a mouse, keyboard, joystick or more depending on the profile sent. And app devs can't create apps which are capable of making use of this service to double the smartphone for input. With the Substratum theme engine app installed plus a necessary add-on app straight from Google Play, users could apply downloadable themes to almost their entire phone all without the need for root access.