> can this dual-pixel format be represented as a DNG?
Same way it is with Fuji S5 and other dual-pixel Fuji cameras.
> imagine Canon had adopted DNG as their format
Well, that's somewhat hard to imagine.
> Would there be way to represent this data in a DNG
in a meaningful way, so that not only use DNG as a container, but specify the "meaning" of the extra data? So that converters would "know" what to do with it?
That would mean publishing the document that specifies what are the interpretations for Canon undocumented Makernote tags