I'm not sure what the difference between the two are, except that one has a battery and the other doesn't. For what it's worth, here's the product link for the m5stickc: https://docs.m5stack.com/#/en/core/m5stickc
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.
I've just flashed the same binary to my m5 atom matrix https://docs.m5stack.com/#/en/core/atom_matrix which also has a pico-d4 but this one is stable and has been running the neopixel code https://www.espruino.com/WS2811#software for about 10 minutes now.
I'm not sure what the difference between the two are, except that one has a battery and the other doesn't. For what it's worth, here's the product link for the m5stickc: https://docs.m5stack.com/#/en/core/m5stickc