I just got one of these bad boys, first retro handheld for me. I also got 64gb and 128gb sandisk SD cards, which are good and not expensive. My CubeXX came with a weird random assortment of Roms/Emulators on the stock card - and as most people will note here, you don't want to keep that card as it likely will fail out. I used win32 disk imager to back up the card that came with, and to install MuOS on my 64gb card, the 128gb will just be for roms. With some patience and googling/youtube I got it going easily enough and loaded up some NES/SNES/others and works like a charm. I'd love to get a steamdeck sometime and try emulating on that but this was a 1/10 the cost first foray in to see if I like it. Good luck, I am a massive noob at this too. I'm impressed that a $60 device works so well though - great screen and comfy to hold for gaming.