You could do them in stoneware in the oven, but probably not the microwave.
The main reason the recipe is to do them in the skillets is to show how the cookware can go in the oven, not just stovetop
As for the 8" vs 10 or 12" - I bought the big can of Grands Bisquits and yeah, they were never going to fit in the 8" pan. I borrowed the 12" skillet from a teammate and made them in there for a show last weekend. There was plenty of room in the 12" pan! If you buy the regular can of bisquits that is smaller then I bet it would fit in the 8" (that sounds like what others are doing anyway).
The main reason the recipe is to do them in the skillets is to show how the cookware can go in the oven, not just stovetop
As for the 8" vs 10 or 12" - I bought the big can of Grands Bisquits and yeah, they were never going to fit in the 8" pan. I borrowed the 12" skillet from a teammate and made them in there for a show last weekend. There was plenty of room in the 12" pan! If you buy the regular can of bisquits that is smaller then I bet it would fit in the 8" (that sounds like what others are doing anyway).