Just found this and thought it would be of interest to scribus users.
https://bottosson.github.io/posts/colorpicker/
Interesting topic, it is true that most color pickers today just seem to be made to make it possible for you to choose all possible combinations of the "numbers". But they are not really well suited for visual color picking.
I realise I often first pick something close to what I need, and then I adjust it manually...