@felmue
Thanks, Felix.

I sometimes try Core2 examples, as it seems to have more documentation. The M5Unified example is working on the Tough. I commented out the initial module statements:

// If you use ATOMDisplay, write this.
//#include <M5AtomDisplay.h>

// If you use ModuleDisplay, write this.
//#include <M5ModuleDisplay.h>

// If you use ModuleRCA, write this.
// #include <M5ModuleRCA.h>

// If you use Unit LCD, write this.
//#include <M5UnitLCD.h>

// If you use Unit OLED, write this.
//#include <M5UnitOLED.h>

// If you use UnitRCA (for Video output), write this.
// #include <M5UnitRCA.h>

...and the display shows the menu with the buttons.
I see they have the wave file directly in the .ino, so I may try and translate my mp3 to hex and paste it in where the wav_unsigned_8bit_click goes.

This definitely gives me something to work with, so thank you.