Oh wow... makes sense, just never realized that.
Very dumb example for this...you take a matchbox. Then a USB-cable. One side into the PC, other side...mhm hold on to the box or put a match into the plug?
Sure thing it does not work, the USBus cannot distinguish between tree, wood, match brand and the number of matches. It can't even see the status change 'now something's plugged in', even if that worked, the matchbox wouldn't respond to the USBus when asked 'what device are you?'.
Two devices must speak the same language and for the answer alone 'I'm a 2GB pendrive, vendor:sandisk etc.' it needs to have firmware.
Or that it could be upgraded/ changed.
That option is not always available for the end-user. If it is not provided by the manufacturer, then the target device does not have a software interface for it. Also, if there is an interface, there is no guarantee that the manufacturer will give you software to flash it, nor will they give you a firmware file, if they have one at all.
Anyone have any advice that is firmware related to buying refurbished EXOS drives on ebay?
Focus on generic drives (with generic firmware) without third party branding, avoid the drives pulled from storage applications to avoid vendor locks. If the seller doesn't mention it or the label doesn't tell, choose another.
If you get seduced by cheaper prices of third party disks, then search around here if you find a success story for exact this model and if it can be reformatted or crossflashed to generic firmware. If not, you could try your luck or regret it.