CWK-245 Can A pedal be used to transpose (Key change in real time)?

[aspis]

Hi,

Greetings. This is my first time here. I am trying to find a way to transpose a song to a different key during playback. This is something my 80 year old father wants to do with his Casio. He is a a guitarist and often in the process of using backing tracks that he has written (or in the process of writing, looping etc.,) he needs a hands free way to make a key change when composing etc.  Having to take his hands off the guitar to do this disrupts his loop building and recording session. Would a simple pedal work? If so, which would you recommend? He doesn't need anything complex, fancy or expensive. Just someway to do this one thing.