I can’t understand how they came up with the idea of using an 8-bit DAC. The poor-quality DAC becomes even more unusable due to the presence of the pull-up resistor.

Remove the resistor, and you will have another DAC with the same functionality.

It’s time to forget about Arduino Pro Mini and move on to something 32-bit. Wemos S2 Mini ESP32 Development Board with a price of 1.00 EUR looks promising.

And let’s see if MicroPython is usable for prototyping.