So cool! I implemented support for zenoh-pico about four years ago for the first version of the rmw_zenoh implementation, you can still find it in the archived branch of rmw_zenoh
The advantage of my implementation is that it shares as much code as possible with the regular rmw_zenoh, so it should be easier to maintain and keep up with any improvements in rmw_zenoh.
I didn’t need to use micro-ROS at all, I got the whole ROS 2 stack running on a microcontroller running Zephyr (and NuttX? I can’t remember). I can’t remember the specs for the microcontroller, I must have been an STM32 and I’m pretty sure it had at least 1MB of flash memory.
Anyway, really cool to see support for zenoh-pico in ROS! Let me know if there’s anything I can help with, I had a bunch of ideas on how to improve it, but I don’t know if they would work with the current rmw_zenoh, though.