Zephyr is an excellent real-time operating system：
Libcanard is already being leveraged with Zephyr. There is no additional porting/adaptation necessary, it works out of the box.
@PetervdPerk might tell you more.
Libcanard should work easily with Zephyr however you’ve to configure/setup your CAN hardware driver.
There are 2 options:
- Enable SocketCAN in Zephyr and utilize the SocketCAN HAL located here https://github.com/UAVCAN/platform_specific_components/tree/master/socketcan/libcanard
- Write a simple HAL layer that uses the Zephyr zcan_frame api see Controller Area Network (CAN) — Zephyr Project Documentation