Building any non-trivial system based on DroneCAN today would be a mistake unless you strongly require compatibility with legacy hardware out there. This is because of its inherent architectural limitations, which are covered in the Guide. I am fairly confident saying this since I was more involved in the architecting and designing of both DroneCAN and Cyphal than anybody else.
Cyphal/CAN is already supported in PX4. Although the support might be considered somewhat minimal, it should be easy to extend since the hard part is already done (mostly by @PetervdPerk, @JacobCrabill, and others).
Cyphal/CAN is minimally supported in a fork of ArduPilot. There is an upstream pull request which appears to be failing to gain the attention of the maintainers but one might hope to see it merged one day.