The rust standard library support was not that complicated to add because a) esp-idf ( with the FreeRTOS kernel) is used underneath b) esp-idf has unix like f

The rust standard library support was not that complicated to add because a) esp-idf ( with the FreeRTOS kernel) is used underneath b) esp-idf has unix like features and exposes a posix layer for stuff like networking and filesytem. If you want to look at the full initial PR on rust-lang github look for PR number 87666.