You could get some Roms, searching for them on the internet. People have dumped the files and made them downloadable. You’ll need to download them from the internet. If all things go according to plan, they will be on your computer. Then you can transfer them to your gameshell.
Otherwise, if you own cartridges and the original consoles they run on, you will need a “game backup” device. I had an MT-2 for my snes (which sat in the cartridge slot) and a CD64 plus for my N64 (which sat underneath)
I would legitimately own all of my games, and use the backup device to apply IPS patches, allowing me to translate Japanese games into English. Got to play some amazing Japanese snes RPGs at full speed with the correct sound emulation etc, on real hardware.
These days, I’m not sure how many people still use them. I personally do, but not as often as I used to.
