I think I know what the OP means.
I run a whole 'kennels' of Puppies. I use a 128GB SanDisk Ultra 'Fit' (nano-sized) flash drive, plugged into our home router's USB port, as a make-shift NAS.
Easiest way to access it is through Samba. Your router is invariably
Since there's only 2 machines on my LAN, I often access each machine from the other via Samba anyway, but sometimes want something on the 'NAS' that's commonly available to both.
Pup's also got FTP, too, but I never got the hang of that. I use
rcrsn51's Samba-TNG, a lightweight 'fork' of Samba, which has been available for Puppies for years......and which has proven to be remarkably robust.
(Michael's quite right; it won't be a 'proper' NAS, the same as mine isn't.....but it'll give you an approximation of the real thing.)
Mike.