I thought they could be useful for e.g. boxed lunches at a conference, or printed on a "mom and pop" restaurant menu, or in a cookbook, where maintaining a central database isn't really practical (aside from avoiding tracking).
It would also be easy to encode things like "Vegan" or "meat-free" or "contains nuts" which could be helpful to blind/low-vision folks or people who don't want to read through a 50-ingredient list to find out something contains shrimp extract or whatever.
I only got as far as setting up a domain (https://nut.codes) and a couple of aborted attempts at prototyping (https://github.com/nut-codes).