P: Expanded Curve or Levels view with color coded channels
In Adobe Camera Raw (ACR), the HSL tab can be expanded to view and adjust everything at once.
It would be nice if it could be done on the tab of the adjustmet layer of Photoshop.
Curve or Level (RGB, R, G, B) So that can see and change it at once.
Also, This is extra, but it will be more intuitive if the color of each channel is reflected in the histogram, as is the curve at the level. It's not necessary, but there's no reason why it shouldn't be applied.

