> Camera sensors from different companies (and different generations) don't have the same color (or if you prefer, spectral) responses with both their Bayer filter layer and the underlying physical sensor

This is all accommodated for in the DNG spec. The camera manufacturers specify the necessary matrix transforms to get into the XYZ colorspace, along with a linearization table.

If they really think the spectral sensitivity is some valuable IP, they are delusional. It should take one Macbeth chart, a spreadsheet, and one afternoon to reverse engineer this stuff.

Given that third party libraries have figured this stuff out, seems they have failed while only making things more difficult for users.