Okay, I just made a matrix ICC profile from an Adobe Standard DCP for my Nikon D7000, and it works fine. Here are the steps:
$ dcamprof dcp2json <filename.dcp> <filename.json>
$ dcamprof make-icc -p matrix <filename.json> <filename.icc>
In the .json file you can see both the ColorMatrix1 and the LUT; -p xyzlut would make an A0toB0 LUT ICC. For this camera, I made the LUT profile to use with extreme colors, works quite well. I made a similar one for my Z6, but for some reason it doesn’t work so well, need to pick at it. The Z6 is what I’m noodling with measuring spectral sensitivity for, as this to me would be the gold standard for camera profiling.