Currently NuttX has support only for NOR Flash and eMMC as solid state storage.
Although for low-end embedded systems NOR Flash still much used, for some devices that need bigger storage, NAND Flash is a better option, because its price per MB is very low.
In the other NAND Flash brings many challenges: you need to map and track all the bad-blocks, you need to have a good filesystem for wear leveling. Currently the SmartFS and LittleFS offer some kind wear leveling for NOR Flash. It needs to be adapted to NAND Flash.