This should cover every Nintendo game cartridge, but it was made specifically for the Game Boy (DMG/Color/Advance). It currently just counts up the address pins and reads the data, with no defined range to read from.
Next hardware step is designing an adapter to map the pins for each console, and then making a PCB for both.
Next software step is writing cases for each of the memory mappers used in the cartridges... For each console... so only ~50 cases...
I wanted to make this because these universal readers cost ~$150-200 including adapters. Instead, I decided to spend $30 + $1000+ of my time
It's no complete solution anyway.