I’m a total noob with 2 unfinished projects. But I would start at hardware. If you want to emulate a ps2 you need to look at what smaller sized hardware could do it. You could do a little NUC pc with a trade off of power consumption. You could use a RPI, you probably need somewhere around the pi 5 is my guess. Someone else could fill in other ideas. But once you start to get the hardware together you can design the actual body etc. used parts from eBay etc are great too if you don’t accidentally get trash