I use KDE Plasma, and much prefer the KDE color picker over the GTK one that Firefox uses, with input type=color.
I know that I can set GTK_USE_PORTAL=1 to make Firefox use the native file picker, is there a way to make it use the native color picker as well?
I know there probably isn't a way, but I figured it's worth a shot asking.
You have asked all the proper questions for me to have full respect for you and offer a link of my prototype..
https://drive.google.com/drive/folders/1ibb3GnYb_LFqfk-HxlMtfyT8j5Fi2Hjq
Please take note that my software may have glitches, which should be outlined in the readme. I admit it's incomplete, but it's not easy designing a whole new GUI concept on your own..
Sadly I am away from a computer for quite a while so I can't truly test it, but the first picture shows a nice concept of Brightness X Hue between two colors.
I can't say I'm an artist, but I did design the current icon of a semi famous Android app, and I was actually using numbers to pick the correct values, as I wished the colors had a somewhat understandable mathematical relationship between each other