I understand your concerns but DLog-M is not really a true log encoding. So it isn’t as simple as defining a log to linear function. As far as I’m aware it is also tuned per camera depending on the sensor capabilities. There wouldn’t be a single IDT possible.
What DJI could do is provide custom LUT based DLog-M to linear conversions per camera. But this may simply not be on their agenda as the see DGamut/DLog as the premium/pro option. But that’s my wild guess. Until then you can try your luck with that IDT I linked that someone made or flag it as Rec.709 and work from there.