@jpilarski Hi, i agree the M5Stack is indeed a really great device !
Regarding your query, you can review a list of command functions here: https://github.com/Kongduino/M5CheatSheet
Also you can review the code from this excellent working menu system by Tom Such that uses the buttons for selection: https://github.com/tomsuch/M5Stack-SAM
He also created a template program for making your own menu:
https://github.com/tomsuch/M5StackSAM