Not sure if anyone is interested, but I recently got a Pong 2 player countercade and truly am enjoying this as a piece of functional furniture.
I did take it apart to discover different I/O ports. USB/A and Micro and even an SD card slot.
I plugged in a usb hub to the port and attached 4 controllers. I even plugged in original Atari paddles and a Hyperkin Ranger using a USB adapter (2600-dapter II) and it worked flawlessly for 4 Player Warlord.
Just wanted to document this somewhere for anyone interested in the slightest.
I'd love to be able to put that SD card slot to good use though.