AFAIK the idea that cravings represent desires for specific nutrients has been largely debunked. Do you know of any material that supports the theory?

Debunked by whom and where. I'd be interested in getting your sources too.

In terms of material supporting the theory, google "pregnant cravings nutrients" and you will get hundreds of results... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5054961/ https://familyandconutrition.com/food_cravings_pregnancy/ https://www.webmd.com/baby/features/pregnancy-food-cravings#...

> Has she figured out ..

I wouldn't dare call it "she", "knows", "exactly", in the strict sense, but the less-than-conscious parts of a human should have a pretty good though fuzzy experience of what foods are beneficial in which circumstances.

Are you maybe thinking of pica? https://en.m.wikipedia.org/wiki/Pica_(disorder)

AFAIK, dirt and feces are rich in cobalamine (vitamine B₁₂), which is otherwise scarcely available in non-animal sources.

Calling it a "disorder" and "largely non-nutritive" seems a bit broad, when it could be satisfying a particular need. Even though eating feces might not be a good idea and more serious examples do seem useless and damaging.

I also thought it odd that the article (or perhaps broader academic community) characterizes these behaviors as necessarily disordered. There seems to be a logic to it.

Surely you'd have heard about it from friends or family if it was common for pregnant women to have cravings for nails and bottle caps and that their bodies need the nutrition from them?