Maybe this is not intended here, but I wanted to have an eyedropper functionality in JOSM to pick colors from imagery. There is only an old request https://josm.openstreetmap.de/ticket/8935 from a decade ago, stale since 5 years ago from administrative activities.
Here, the panel could show the main color found, and allow copying of its hex code (and perhaps closest color name if possible), for tagging *colour=. I believe this will be helpful for Magic Wand usage in the first place, to learn what landscapes and colors work best. Ultimately, it could evolve into a new functionality, a separate mode that allows selecting all pixels in view or selection that matches the color according to the options. (I don't know how useful it will be)