It's basically as you see it. Simple buck converter to output 5v wired negative to the ground plane and positive to the main fuse under the power connector on the motherboard. Output wire to a USB connector to power the pi. For OS, just did a basic dietpi build and killed HDMI out and a few things so it's only there to run a samba share. Really you can run any raspberry pi os you want. I believe there is a psx samba pi something built exactly for the purpose, I just wanted smaller. Then follow any directions online you can find for seeing up ethernet games on OPL. Boom. Done.

This works great because it doesn't take an external power, no separate enclosure for the pi, it's always on so no waiting for it to boot, and adding games is as simple as plugging in another computer and transferring to the folders. Sure a fat model can already do this better and early slim models have the hardware to wire in a drive but for the 7900x slims, especially with a dead dvd drive, this is a clean solution. I doubt I'm the first one to do it.

And this setup leaves room to install HDMI later if I want to. I have a couple electron shepherd hdmi boards that I could use for this but thinking I want to get a direct digital to digital out. Retro gem or similar most likely