Or, actually, SD Cards.
So the idea is basically the inverse of what the "Nintendo Playstation" would have been. Instead of a console that originally used cartriges using CD-based games, a CD-based console using cartridges!
Could the PSX be reverse engineered to accept SD cards? I mean, there were people running games from an HDD on the PS2, and the PSX was notorious for having bad CD drives (on some models the drive wouldn't read unless you flipped the console upside down!), so it could be really useful and cool!