This is one of those "do we really need to do this" type of things. If you go and play with an OKLCH tool like this one, you'll notice that the differences in the OKLCH vs RGB/hex color are imperceptible: https://oklch.com/#65.88,0.2097,41.29,100.
See the part on https://evilmartians.com/chronicles/oklch-in-css-why-quit-rg... and notice the cut out in the right column. Now pretend to stretch those cutouts to fit the edges of the chart, you'll have a color gradient that is more uniform across the board versus the left where you have darker areas.
They sold HSL to us as a way to vary the hue easily in a way that's not possible with #000000 without manually computing it first. The reality is that the hue parameter in HSL also considerably changes the luminosity of the color.
The tool you linked only demonstrates that OKLCH can also display colors that rgb() can't, but most of them are the same.
if im doing color-anything, i do enjoy manipulating the raw colors over any integer representation of them, then sending whatever code i need back to whatever.
im more irk'd at the main linked page, shows up nice and dark background, then scroll down a hair and its back to staring at the day-star, ie white background and eye killer. why oh why? ha, if i scroll up and down fast enough its like a strobe light. weeeee. and there was another HN page related to oklch themes yesterday that did the same thing; making me improperly biased already.
please folks, dont make a mess of my dark mode