So I have similar specs, and have been following this site https://howchoo.com/g/mti0oge5nzk/pi-cart-a-raspberry-pi-retro-gaming-rig-in-an-nes-cartridge and was directed to come here when they couldn't figure out the same issue @skrapps914 is having.
Plug in all USB devices first, then power, USB Hub light comes on, which also had worked when on desktop. Decided to directly connect keyboard and/or gamepad without HUB so was directly to the USB to mini USB to Pi 0. Still nothing showing in Emulation Station. Had to directly disconnect the power and reconnect and start over, still no dice. Went from a 2.0 Amp to a 2.5 Amp, no difference.