this is awesome. i was just thinking recently about improvements in a colour picker and wondered if there'd be a way to limit it's range (to f.e. fix the saturation, or limit it). (obv depending on colour space what could have a min/max)

The issue with some of this stuff is without a standardised UI for the picker there's no guarantee that the underlying UI actually supports those kinds of additions. Whereas alpha support is standard across OSs that have a colour picker. Browsers can add it to their custom UI too.

Even supporting display-p3 is tricky because lots of code still assumes RGB.