Reading this post made me look into HDR more, and I do think it provides a very noticeable improvement.

I run on a cheap 4k HDR TV/monitor, and HDR has never looked right in games, but I noticed in the monitor settings that there is a calibration program you can download and use to calibrate windows to your display. It turns out my white level was way off, so everything looked way to bright. Properly adjusted it looks very good now.

FWIW, I have never been able to get HDR to work with No Man's Sky either, but now that looks really nice.

I use Willybach's 4k texture pack, which makes Valheim look amazing. With HDR now it looks even more amazing. So much so that I sailed past my base last night because I was mesmerized by the moonlight reflecting off the trees and terrain.

This vid doesn't look great on my monitor. Native Valheim HDR support in Win10 looks better than that on my monitor but I could believe the local dimming isn't fully utilized like the author suggested. I would like to see more contrast in tombs and crypts.

Valheim HDR is subtle. Red runes on a rock at dawn is most obvious. The atmosphere gradients or something feels smoother but they are pretty smooth already in SDR.

actually can't be sure it isn't just scaling SDR to HDR. Hard to compare when the sun is on the move.

I found this
https://www.youtube.com/watch?v=13ruyxmUEyM
Not really much info about.