I suspect that the iPod nano is somewhat un-hackable, but the iPod mini and earlier models actually had physical mini EIDE spinning disks in them. The interface was electrically identical (or close enough) to CompactFlash cards that a little service I ran on the side for beer money was upgrading people’s iPods to CF. Nowadays you can get absolutely gargantuan CF cards. I put a 256GB CF card in my iPod mini and the firmware, to my surprise, had no trouble recognizing the capacity. I also personally love that form factor, but obviously, different strokes for different folks.

I do appreciate that you said that you enjoy curating your 8GB but I got tired with that way back in 2003 when I bought my first iPod. I never want to go back to that.