btw, the reason i'm bothering with dumping the firmware is because Anbernic doesn't list the firmware image for a 64GB card on their website for whatever reason. Since they have separate images, I doubt their 32GB image is smart enough to auto-expand to fill a 64GB card.
So I'm dumping the whole card before I put muOS on it, so I don't have to faff around looking for a firmware image if I ever want to switch back.