This project makes a keyboard, video display, and mouse (KVM) by replacing the motherboard in a broken laptop with a Teensy 3.2 keyboard/touchpad controller and a video converter card. In addition to the standard crashcart KVM features, this KVM can be switched into a Raspberry Pi laptop. The Teensy replaces the control pad for the video converter card so it can select the VGA or HDMI video source. A 3PDT switch connects the Teensy USB with either the server or the Pi.
The steps to build a Pi KVM is documented at https://www.instructables.com/id/DIY...led-Laptop-Pr/