Tested with 10-bit mode on KDE on an M1 Pro.
- 10-bit mode: 0..1023
- 8-bit mode: 0..255
- Likely native primaries
- Actually seems to be P3?
- 10-bit mode: 384..896 range for white, gamma looks normal.
- 8-bit mode: 0..255 slightly wider than native gamut (reds clipped)
- BT.2020 (with the bg-sRGB range in 10-bit mode)
- 10-bit mode: Like 9, but with noticeably less saturated primaries at 896. With the extended range, reaches the same saturated primaries as 9,12.
- 8-bit mode: almost certainly sRGB
- Likely sRGB/bg-sRGB.
16: HDR (PQ). Doesn't actually increase dynamic range in any way? Clips out at 50% (512) and also has more range devoted to dark/black colors.
Others: Normal SDR. Presumably the sRGB transfer function.
1: BT.709? (not explicitly supported)
Fun thing: with HDR mode and "others" colorspace, pure green overflows the red channel beyond whatever negative saturation headroom they have, and it ends up wrapping around into yellow.