alt Hacker News> This seems more like a replacement for Styrofoam rather than cardboard boxes
It seems rigid though, more akin to cardboard than soft styrofoam. I don't see anything about how dampening it is, but from the pictures I also assumed it was more like cardboard than styrofoam. Maybe the color is deceiving me though.
https://magicalmushroom.com/mushroom-packaging
Under "Features" it explicitly calls out polystyrene as what it is meant to replace, and under "Performance" they claim to provide for clients "that demand the same technical performance as the polystyrene we replace"