It doesn’t seem like 10 bit
It doesn’t seem like 10 bit native panels would be that hard to do. Perhaps TN technology has some limitations that make it hard to do? I have an old panel that is 10 bit capable, but it is IPS based (dell ultra sharp U3011). If they could do 10 bit back in 2011 or so, then it doesn’t seem like it should be difficult now. It was about 1500$ new though, so it wasn’t cheap back in 2011; I bought it because I wanted 16×10 form factor and it was also the last of the CCFL displays. Most LED backlight displays I looked at had terrible color accuracy by comparison. It took them a while to get good color accuracy with LED backlights. The U3011 can use close to 200 W to achieve excellent color accuracy though, so I am kind of waiting for 4K at 120 HZ, hopefully with quantum dots as an upgrade. The power consumption on the quantum dot TVs seems quite good. It produces very narrow frequency ranges, so that translates into higher efficiency and better color accuracy.

6-bit panels are ridiculous.
6-bit panels are ridiculous. It would be nice if HDR capable panels are all at least 10 bit native. I have seen some cheap HDR TVs that sounded like they just support accepting HDR input; that is they aren’t actually an HDR capable display other than the electronics to convert it to something that the mediocre panel can display. They definitely need some standards here. I don’t know how much difference there is between a true 10 bit panel and an 8 bit panel with dithering. A 6 bit panel only has 64 possible brightness levels for a sub-pixel. I assume the laptops at Best Buy with cheap TN panels are probably 6 bit. Those look like garbage, but that might be due to other things, not just the bitness of the panel. An 8 bit panel would be 256 and a 10 bit is 1024 levels. If you are going to have a significantly higher max brightness, then limiting it to 64 levels is not a good idea.

Probably because 6 bit isn’t
Probably because 6 bit isn’t HDR.

The 400, 800 and 1000 are in
The 400, 800 and 1000 are in reference to peak light output measured in cd/m2 (or nits).

The bit depth is only part of the spec. Also it is a minimum for each level and could vary giving us a DisplayHDR400 with a 12bit panel and a DisplayHDR1000 with a 10bit panel if a manufacturer so chose.

Regardless this is very exciting news.

Not really VESA is big
Not really VESA is big https://www.vesa.org/about-vesa/member-companies/

May be relevant…

and panels with dithering sit between with a ranking of 700 or 900