Could you clarify whether Mori coating used during processing, then washed off before sale, would count here? Or must it remain on supermarket food and replace its plastic packaging?

Tufts reports silk-treated spinach reaching major Northeast retailers, but Mori’s FAQ says current market uses are washed off before reaching consumers. I have not found a named chain or evidence that retail plastic packaging was replaced, so I would not assume YES from these sources alone.

https://solutions.tufts.edu/expertise/sustainable-materials/edible-food-wrapper-help-reduce-waste

https://www.mori.com/faqs/

An Edible Food Wrapper to Help Reduce Waste

Breaking silk down into its fibrous protein base, researchers at the Silklab at Tufts University have devised an edible coating that helps extend the shelf-life