I have a modified Nintendo Wii that can run backup game files (via external media, IE; flash drive, sd card, external HD) and an always on PC that sits right beside it with tons of storage. I'd like to just run a USB A to A between the two from a drive (or partition) on the computer that's set to emulate a flash drive/external hard drive via the USB port. Is this possible?
You would need a PC with a device USB port. I've never seen them on laptops or desktops, only on tablets or phones. See this answer for more information.