Nice. Have you thought about making the firmware "self-hosting" - a version that runs on the WCH32V003? Then in future it may be possible to buy a development board that is pre-flashed with this: a simple way into microcontroller development, similar to what can be done today with an Arduino board, and bare-chip Arduino "cores". The only Arduino part that is really needed is the ArduinoISP sketch for firmware flashing and afterwards that framework can be forgotten. Use of your firmware could be similar, but even less costly: 5-10X?