"I don't know any device for commodity computers which allows raw NAND access."
It's not pretty, but there used to be a USB XD card reader chip called alauda which would expose the XD/SM card ( they are both basically repackaged NAND chips ) as an MTD. Linux drivers are in the tree I think.
Useful for little more than experimentation. And only then if you're good at hunting for one on ebay.