The MERG CBUS is a high level messaging layer that sits on top of the CAN transport layer so in theory you could create a wrapper for the due that emulates the API of the Pico CAN bus library.
Alternatively just buy a Pico and write a communications interface that allow the Due (or any other microcontroller) to send/receive data using the Pico as a proxy. This will insulate you from needing to know anything about the low level aspects of CBUS or CAN.