How to emulate thousands of games on original arcade machine?!

So I came across this video of Jace (an artist I listen to) showcasing his new arcade machine setup. As you can see in the video it's some sort of emulator with thousands upon thousands of games from different gaming consoles. If anyone with the right knowledge can kindly break this down for me on how to reasonably achieve this same setup regardless if it's expensive, i'd appreciate that, thanks!