Don’t use the PQ histogram neither the hlg as they appear to be broken.
Looks at the PQ histogram, it shows that in your image there are a lot of data at 10000 nits and i don’t think this is the case.
Same issue for hlg, however hlg has a pure gamma (2.2 or 2.4) from 0 to middle gray for legacy display, and a logarithmic shape in the upper part, so i don’t really see why it should be better than srgb.