Oh and as an announcement of my own:

* I'm working on a network stack (think of it as the next version of postcard-rpc): https://docs.rs/ergot/latest/ergot/book/index.html
* I just got it working (at least parts of it) on the nrf52840: https://github.com/jamesmunns/ergot/blob/e0918e461d70200b11136d88131775b580259dab/demos/nrf52840-null/src/main.rs
* If anyone really wants "message passing everything", it might be ready to use for you today, I hope shortly to get the actual "inter device comms" part working on embedded in the next day or so :)