Color temperature is not what's being talked about here; that's just a small subset of color management. HDR is also not about bits, but color space, which requires profile support.
Even 10 bit support is another issue. A few composers have alpha support recently, but it isn't something you can expect to use.
Wayland (proto) supports 16bits per colour. (Much more than HDRs 10 bit) https://github.com/wayland-project/wayland/blob/6741dafbf7a5...
It’s up to the compositor to enable them.