I suppose ESP32-based modules usually carry networking and USB hardware which is immediately usable, without esoteric IP licenses, don't they?
The wifi bits are closed-source blobs. The rust embedded community has reverse-engineered some of it for some chips, but not sure how complete that work is.
It's worth noting that the support for ESP32 in Rust is official [0], and there are multiple full time engineers at Espressif working on developing and maintaining it.