Just about every site I checked on said SSD’s should be good for about ten years, whether used heavily or not. Flash drives they recommended plugging in and reading every once in a while…

Optical disks otoh, yes, if you want centuries out of them you’ll need to purchase expensive archival type ones, but longevity of even normal ones is several decades and they don’t need to be used occasionally to keep them functional.

So, in practice, for data you simply want to put in a cupboard and dig out 20 years from now, the sites I checked don’t recommend NAND storage.

Now, where did I put all my ZIP disks?! 😂