I once enquired of a punch maker the cost of getting such a punch.
A punch for "Decora" or "GFI" rectangular holes posed no special problems, and I think a price of several hundred dollars was quoted.
As for the usual "double D" duplex...well, making that was something they "were giving some thought to", but it posed several challenges, and they weren't sure they could do it in a manner that was both affordable, and able to operate with the tools available in the field.