These are valid DNGs and should work with any application that fully supports the DNG spec or uses the Adobe DNG SDK. But they are not supported by the GainMap implementation in either ART or Darktable master.
The typical smartphone DNGs that are supported by those apps have the GainMaps in OpcodeList2, which are applied to each color channel separately before demosaicing, and correct both vignetting and color shading at the same time.
But these DJI DNGs work differently - in OpcodeList3 (to be applied after demosaicing) they have two separate opcodes. There is FixVignetteRadial which fixes the vignetting and has no effect on color, and there is a GainMap which only affects color shading.