I bring this up as for some workflows, Rust is one of the easiest "just works" embedded toolchains/workflows; my experience here was jarringly different, especially as it had been a good workflow prior. On this project, I ended up switching to ESP-Hosted (Official Espressif firmware to let the ESP be a radio co-processor), writing my own Rust lib to interface with it over SPI or UART, and using an STM32 as the primary MCU running my [rust] firmware.