

If I were handed that hardware, the first thing I’d try is…
If what is currently being used is usable, and I don’t want to risk making it unusuable, shrink/resize the active partition with a partitioning tool. Then, assume I’m multibooting and I’d install on the secondary partition:
Raspberry Pi Desktop. I’d choose Pi OS because it is designed for an ultra low power 700MHz ARM11 that comes with the 2012 Pi 1. The drawback is it’s an older Debian install (Bullseye), but still getting long-term support until August. I assume they will release a new Desktop version when that date comes.
RetroPie. I’d grab the RetroPie script for ease of use on installing SNES emulation. It should prompt every emulator choice available for your system, and set up controller support (or keyboard+mouse) and emulationstation so you can browse your legally dumped roms after putting them in the correct directory.

that’s good for testing if a device will work or not, but it’s terrible for judging how the OS performs. Mostly because your DVD/USB is going to be a serious bottleneck for I/O. Combine that with the 4GB of RAM and you’ve got some potentially crunchy performance ahead of you, which would not be indicative of the install performance.