Customising output bit depth, color format, dither, deband, hw resizer

I'm running Libreelec 13 nightly on a PI 4B and a Samsung S95B tv. I would like to customise the HDMI output to my tv, instead of a fixed 12-bit RGB with 10-bit content and 8-bit RGB with regular 8-bit content and the GUI. It looks like Libreelec takes the highest bit-depth reported by the EDID, which is 12-bit for my tv. However, since I play 10-bit files at the most, I would like to output as close to native depth as possible. I don't trust what my tv does with 12-bit, since its panel is 10-bit, it might just truncate the last two bits, so I'd rather output 10-bits instead. I would also like to control the dithering, if applied. When playing 10-bit HDR white ramps and color gradients I see some flickering 'snow' or 'noise' on my display, suggesting temporal dithering is being taking place. I would like to control applying temporal/spatial dithering and favour rounding. Similarly, i would like to control the hardware resizing algorithm and debanding, if possible. Other settings would be custom YCC chroma subsampling and output range (limited/full). Kodi option for the latter doesn't seem to affect the video output.

I've tried using hdmi_ options in config.txt, such as hdmi_pixel_encoding, hdmi_force_mode, hdmi_deep color, hdmi_drive to force KMS but they doesn't seem to affect the output of cat /sys/kernel/debug/dri/0/state. I've also tried adding parameter to cmdline.txt such as video=HDMI-A-1:1920x1080-10@60eD,color_format=RGB, but it doesn't affect the output, it seems hardwired to 12-bit RGB with my tv.

Is there a way to pass kernel options or modify filesystem node parameters for the KMS to customise these settings?
chewitt  HiassofT