Necromant designed and built an Android TV stick baseboard:
The idea was dumb simple. I needed a USB hub, since TV sticks don’t have many USB ports included. I needed GPIOs, so I threw in an attiny2313 that occupied one of the HUB’s ports, I needed a few relays and I wanted to control the power of some of the ports. Since TV sticks have their power input and usb power connected you can just supply power for the stick via the USB host port. Finally I wanted this whole thing to work from a 12-24V power supply, so an on-board 3A DC-DC was a must.
More details at Necromant’s project page.