An addition to the eyedropper tool's abilities where you click on an area and it shows metadata of the name of the brush that was used, size, and opacity.
Not sure how you envision that to even work. Once a brush has been applied it's just pixels and the old "million ways to skin a cat" analogy applies. You could use totally different brushes that produce a visually identical result. Unless you are talking about something very specific like scatter brushes or pattern brushes that have distinctly recognizable elements I can't see it working on any level even with the smartest AI-based functions. And even under best conditions this would still be suggestions most of the time, not exact matches. There's just too many factors that affect the appearance like opacity, layering of multiple strokes, orientation, color, blending modes and so on.
Sure, this is how I'd image it to work. At the bottom of the "Info" panel for the Color Selector tool there would be a small section detailing what brush was used. Would be great to have a "quick apply" button too, so you can easily get back to the brush you used for that area.