Some municipalities actually have separate stream food waste composting, which is great, but rare. Turning solid waste in sewage into fertilizer is a thing (I don't know if it's most places or not, i think not), but is pretty problematic in how it's done, it's a pretty toxic product. Definitely not the same as a composting toilet.
https://missouriindependent.com/2024/08/09/fertilizer-from-h...