Grisha mentioned that you can use coffee as a developer. It turns out that a fairly standard mix uses coffee (instant coffee only) and vitamin C powder! There seem to be lots of different knock-off developer, stop, and Photo-Flo variations using common drug store ingredients. They obviously have different effects on the outcome, but the results are surprisingly good, once you’ve adapted to the nonstandard materials.
This was a clear video that also provides a short review of the developing process!