Looks like Waveshare suggest there are demo files for MicroPython, but I couldn’t find them! (just C).
I couldn’t find a microPython library elsewhere either for the display driver chips on this board.
I think you might want to try a DIY solution to this one with some better supported hardware.
Adafruit sell matrix displays that talk over I2C and have CircuitPython libraries (their fork of MicroPython) and it looks like it has a dimming function, so you’d just need a light sensor on the I2C bus as well so a Pico W could read the light and set the brightness: