I think it is certainly primarily the white perspective (ie Ernest's), as per the title, but the impression I got was the government investigation elements were pared back in favour of more (if not necessarily a predominant) Osage POV. For instance, in sequences where her mother sees the owl, and that rather touching death scene later on where the ancestors appear. And there are other moments with Mollie that are from her point of view a lot more.

And yes, interesting point of comparison with The Power of the Dog and the shifting of timelines. :)