I don't know if this will be helpful to anyone, but just in case:
With COVID-19 virus, I'm stuck at home, of course. I had a little leakage a few days ago that "burned" a patch of skin next to the stoma. I wanted to put some sort of barrier between the skin and the bag, and had nothing. Thinking it couldn't hurt, I dabbed on some calamine lotion with a cotton puff. Voila. Soothing and healing! Who knew?