I’m just adding to the conversation that the safety of using composted human waste on food producing gardens is not guaranteed.
Realistically composting human waste is only feasible for rural residents. The logistics of obtaining sufficient quantities of material and storage become probematic. Buying bales of peat will probably not be possible after shtf. How many bales per person are required for a year? If I need one bale per month for each person then I need to store 12 bales times my group number. An equal amount of space is required for saving poo in piles for a year and a half.
Unless you live near a sawmill sawdust is out of the question. Most sawmills are in rural locations although there are a few in overrun suburban locations.