1. Parts
2. Various cheap items without brands
3. Obvious "overruns" of a branded factory smuggled out the back door
4. Additional runs of a factory that is no longer making whatever it was for the original manufacturer
5. Supplies
You find some printer stuff in 1 and 5, and I saw a few that might be 3 or 4.
Nobody in China is bringing up ancient equipment lines (and it would likely be way more expensive).
At most, you might be able to find someone somewhere (if you have the right connections) that can get you a default firmware for some known printer that is OEM'd to everyone. I know these have been found for things like smart bulbs and other firmware'd devices.