Got my hands on a Dell Latitude ON module. Turns out it’s nothing more than a 2 GB flash module that fits in a mPCIe slot and is wired to the USB lanes. Shows up as /dev/sdb.
I do have a couple of old laptops that don’t have a secondary SATA drive slot, but do have open mPCIe slots with USB lanes (no mSATA lanes). The Latitude ON module would allow for a dual drive system, albeit a rather crappy one. What would you put on a secondary internal drive if it were limited to 2 GB and USB protocol?
A backup drive ? dotfiles (.config) ? /tmp /var/log /boot ? map it into your home for something temporary - Downloads ? Slow audio files ? If you like to tinker for fun: btrfs / bcachefs could perhaps utilize it for something, like automatically offloading unused/slow files to the slow usb ? Raid ? ;) Create a partition and let zram swap compressed unused memory pages to the usb partition (I think it keeps pages compressed now ?). You can also run ‘usb over ethernet’, so another machine can use it directly - not sure why tho ;)
On a side note. I still use one of my first usb 1.? drives with 32mb in my old router. 32mb is still 12mb more than my first hard drive, and it fits well with the small openwrt packages. It even has a little slide button to select ‘floppy drive’ mode and a physical ‘readonly’ mode. I wonder what the smallest/oldest usb stick people still use, are ?
I’ve got a 16MB MMC card that I use as an offline backup for my password manager database. It’s old enough that it uses SLC flash, so I don’t have to worry about data retention time.
Total tangent, but IMO this is the state of the art in data retention: https://superuser.com/questions/374609/what-medium-should-be-used-for-long-term-high-volume-data-storage-archival/873260#873260