Hmm, this might very well be outside of my knowledge, but isn't 10bit sufficient for HDR10?
How is that 'compressed'? It's the exact same signal that's on the 4K UHD Blu-ray.
Perhaps players generally upsample to 4:4:4 for less distortion/artifacts for processing purposes?
Discs are even 4:2:0, so 4:2:2 is still an improvement, calling that 'compressed'?