Hot diggity, I found... most of the missing components to my old gaming desktop! Still missing a mouse and keyboard, but I've got the receiver (and xbox controller receiver) plugged into a USB hub so I can just swap that between laptop and desktop as needed. And it still runs! Only problem is... half my games aren't working right due to needing internet to verify games are a valid install for some reason. ...and this thing is ethernet only. With the only network jacks 1 floor down on the router.
@Kilroy If you have Wi-Fi and have a USB slot open, I've had an excellent experience with these:
ASUS Certified USB-AC53 Nano AC1200 Dual-band USB Wi-Fi Adapter https://www.newegg.com/asus-usb-ac53-nano-usb-2-0/p/N82E16833320343?Item=N82E16833320343&Source=socialshare&cm_mmc=snc-social-_-sr-_-33-320-343-_-12272020