I recently heard about these units, which are based on the most triumphant EPS32 microntroller. I know next to nothing about them, other than they have VGA output, 3.5 mm audio output and keyboard + mouse PS/2 connectors. They also have a couple of pins, which I hope are I/O pins.
I have some images of people using them for VIC-20 and ZX Spectrum emulation. They are incredibly small – and I have two of them. I will follow up when my PS/2 mouse arrives. I do have PS/2 keyboards, but it has been many years since I have owned a PS/2 mouse. Stay tuned!