Pyanodons Hard Mode adds spoilage through Enable Feature Flags, so that items can spoil even with Space Age disabled.
Any chance Frozen Food could be altered to have Space Age as an optional dependency and work with Py Hard Mode?

Sorry, this isn't happening. I would have to change the code around so it no longer assumed Space Age was present (e.g., automatically creating yumako and jellynut recipes, etc.) and also add support for the various spoilables in Pyanodons... which is a mod that I don't use and have no interest in.