Please don't share this to any hoarders. I don't want to have to stockpile it myself due to somehow it ends up sold out. Never tried this method with gourmet mushrooms. I have used this for making wine. So it is food grade safe. "To make a sanitizing rinse for equipment, dissolve 8 teaspoons of sodium metabisulfite into 1 gallon of water. High concentrations of sulfur dioxide gas are irritating and toxic, so use in a well ventilated area." They recommend a final rinse of the product with clean H2O. Only to preserve the flavors of the wine body The Rinse is not required. Sodium Metabisulfite Na2S2O5 You can pick this product up on most of the big retailers .com Wallie world sells 5 lbs bags for 15.30 USD This is 100% faster than sugar, water, yeast wait 10 days and then cannibalize a PC into a still.
That seems similar to what comes with beer kits for sterilization. You will have to try it with mushrooms and let us know how it goes!