You have to have the right people. They have to like Python and want to use it, but not because they think "C is too hard". They have to be happy writing Python code and confident enough to write modules in C and work on MicroPython itself.

There is some steps necessary to go from "prototyping MicroPython" to "production MicroPython" and many people either forget about them, are not skilled enough to do them (which is fine, MicroPython is about onboarding people to embedded as well) or they feel like these steps make using MicroPython pointless.