A single dance pad can't be used even to get half of the Power Pad because the center square on dance pads is not active. Assuming the Power Pad works inside like a Konami dance pad, the sensors are analog (pressure sensitive resistance), so you can't just hook up the guts to a PI, and you need a microcontroller with 12 analog pins. I don't know if the Power Pad's digital electronics can work with the PI's 3.3v GPIOs. A full solution for the Power Pad 12 button side is to overlap TWO dance pads and use bleeding edge fceumm libretro core: https://www.instructables.com/Playing-NES-Power-Pad-Games-in-Emulation/

@infocorn

The light gun games can be played through lr-nestopia with a mouse, air mouse and/or various PC arcade guns that act as mice. Unfortunately, while there is also support for emulating the Power Pad via gamepad buttons, I've never run across a NES to USB adapter that supported the actual Power Pad peripheral itself.