Sure! Let’s gather the Polyend team on Xmas Eve to get back to work! 
Joking aside, I did search and I do believe there has yet to be a wish made for this specific functionality. There was one this Wish for PC to be mapped to change patterns which currently has 32 votes. I don’t know if/when it’s implemented that PC would be uniquely mapped to Patterns only, or if it would be mappable. Patterns and Instruments seem like they would be the most natural candidates.
Alternatively, you could create a new wish specifically for PC to target Instruments, although I believe this would only work when the Tracker isn’t playing.