Hello, maybe I can help. I'm the owner of MADrigal's Simulators.
The problem is that the CPU used in Nintendo G&W is still unknown. Some people suspect it's a TI TMS1000 or a Sharp MC-501.
They are normal 4-bit MCU's with opcodes, RAM and ROM.
The problem is that the ROM is embedded in the MCU, so you should "decap" them and "extract" the data visually, in a similar manner to what the MAME team does to decode rare MCU's (like Bubble Bobble, for example).
It's feasible but expensive.
To date, no one has ever emulated any of those MCU's.
Thanks for reading.