While the Arduino-ESP32 side is my main focus, the ESP-IDF build ought to be very similar (demo*.ino --> main.cpp, and the header and source libs aren't in their canonical locations by default).

Tobers Multidisplay turns your LED-Matrix display into a widely configurable and customizable message center. For ESP8266 or ESP32 and MAX7219 8x8 LED matrix modules. The display can show time, date, ...