I think I’ve said this in the past but I can’t see any immediate benefit to class-marking for users of sub-250g drones. Under Article 21 of the regs, we can fly legacy sub-250g drones in Open subcategory A1 forever (except for privately-built drones). There’s a question about whether “flying weight” and “maximum take-off mass” are the same, but that’s the only wrinkle.
For the C0 class, the drone must be sub-250g, but also must have a maximum flight speed limited to 19m/s, and must be designed to minimise injury (no sharp edges).
So today there is no obvious benefit to making, marketing, or purchasing a C0-class drone.