Why does pressure cooking of chicken eggs make eggs easier to peel?
Yes, I wrote a post about this a few years ago - the first to describe the method in a home pressure cooker.  The theory goes that the pressure difference inside and outside the egg PLUS the shock of the cold facilitates the detachment of membrane from the shell.  The Kitchn tried and confirmed my method and many of my readers will no longer hard boil an egg any other way but Serious Eats had different results - I don't know why.