Long story short, i've modded my Ps2 guitar to play on the switch! Here are the controls: Green -> Turn Left, Red -> Turn Right, Yellow -> Drift, Blue -> down, Orange -> up. Strum Down -> A button, Strum up -> B button. Shaking the Guitar uses items.

If a more detail explanation is needed I'll be more than happy to show. I've also done a similar control scheme for BotW and there should be youtube videos displaying that as well.