No, having the bare minimum "HDR support" does not mean it works fine. I have a 27-inch 4K 144Hz monitor with P3 wide color gamut and HDR600. This monitor is connected to 2 PCs, one running Arch Linux with GNOME as the DE and one with Windows 11.

Since Windows 11 24H2, with the new color management feature turned on, I can get correct colors on the monitor in both SDR and HDR modes. So it ends up with HDR on at all times, and mpv can play HDR videos with no color or brightness issues.

GNOME, on the other hand, is stuck with sRGB output in SDR mode, so you get oversaturated colors. With HDR on, SDR content will no longer be oversaturated, but if you play HDR videos with mpv, the image looks darkened and wrong. I've tried setting target-peak and target-contrast to match the auto-detected values on Windows, but the video still looks off.