>It seems the only other real contender on the backend is VLC

Does VLC already support HDR content on MacOS? I switched to IINA because of that omission.

I don't know. I have a medical light sensitivity problem that makes most HDR content physically painful for me unless I manipulate picture settings to reduce peak brightness, backlight, and/or contrast in various ways. Between my light sensitivity and my progressive colorblindness, I don't get as much out of HDR as most people do, so I just turn it off where possible.

Maybe some day when I have more external displays with OLED or something else that can do millions-to-one contrast ratios, I'll play around with HDR and see if I can find a way to reliably make it comfortable, but for now I don't own any-- it's just the built-in displays of my mobile devices, and I spend as much time as possible on much larger screens because I also have visual acuity problems.