Can any potatoes be cooked in the microwave?

I bought these baby potatoes from sainsburys and it says on the packet you can microwave them in 7.5 minutes and they will be ok to cook. I imagine they are not precooked or am I wrong?

This got me thinking if I get any potatoes and cut them into small enough pieces can I heat them in the microwave without oil and butter same as with these baby potatoes?

Thanks