There’s a DNG validation tool in the Adobe SDK you can use to check.
I wrote a small program (makeDNG) to rewrap my mosaiced TIFFs into (Cinema) DNG. You may be able to adapt it to your needs.
Separate captures to increase resolution (by skipping demosaicing) are problematic. Alignment has to be perfect, which it almost certainly won’t be if you change focus. I use a micrometer to set focus (DOF ~5 microns) on my film telecine and I can barely see focus move between dye layers. I have to stare hard at the per-channel histograms.
FWIW, for 1:1 slides and negatives, I don’t use pixel shift on my A7RIII.
White light is still the reference for the end result, but to maximize dynamic range and color accuracy you want to capture using something else so you can use UniWB and ETTR. Narrow band LED matched to the film stock is a good idea. I have independent LED control in my telecine and could do separate capture, but I’m not convinced it’s worth the complexity. At least that was my conclusion years ago, but for science and curiosity I may have to try again.
As for a good camera profile, I use a machine vision camera in my telecine, so I had to make a profile from scratch. I used dcamprof and the SSFs from the datasheet. I have big dreams to use the old monochromator I’ve had lying around for years to make something more accurate, but I’m already pretty happy with my results. There’s been some recent discussion on such things here.
My problem is that I’m mostly dealing with Super 8 Ektachrome 160G. The G is for garbage. It’s supposed to be both tungsten and daylight balanced…somehow. The blue channel is trash (huge grains) and the color temperature changes with exposure (typical of color reversal). The trouble is that the exposure (and therefore temperature) can change per frame. I don’t know whether to blame the lab or the in-camera metering more. The 8mm Kodachrome I have seems much more well-behaved. YMMV with slides or other film stock.