Good start would be getting familiar with building for existing architecture, in this case ESP32. If you try your own ESP32 build and possibly try to do some modification to it then addind ESP32-C3 could be easier.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
There is https://github.com/espruino/Espruino#porting-to-new-devices
Good start would be getting familiar with building for existing architecture, in this case ESP32. If you try your own ESP32 build and possibly try to do some modification to it then addind ESP32-C3 could be easier.
Check also
https://github.com/espruino/Espruino/blob/master/README_BuildProcess.md
https://github.com/espruino/Espruino/blob/master/README_Building.md