Especially for embedded work (but for regular software too!) I've bought into the "sans-io pattern" for a lot of the software i write anymore

https://sans-io.readthedocs.io/how-to-sans-io.html

Keeping all of the actual hardware/network/io interface code separate really makes writing unit tests and porting to different computers much simpler

I do something similar. I have all my esp/idf code in one crate and all my business logic in a separate crate. The business crate has no dependencies that won’t compile/run on the host. This is where all my tests live.

This is good advice however it should be noted that many of espressif's other purely software components depend on esp-hal, so you still want it to compile if you use any of espressif's provided components.