KDE Plasma has HDR support. You can check if your monitor is supported by booting from a cutting edge KDE distro like Fedora KDE.

It’s still there 😭

My main gripes with it were that its package repositories were really small and that a lot of installer shell scripts just didn’t work because they used GNU flags of coreutil commands, while Chimera Linux uses FreeBSD coreutils.

These issues can technically be “resolved” with Distrobox, but I just found the Artix Linux dinit version much more usable.