Action/Script to sample color and fill

Yes, it is possible to write a script.

But you can create easily an action by yourself or simple use three shortcuts and one click:

1. (select the Eyedropper tool)
2. left mouse click with the Eyedropper tool (new foreground color from Eyedropper tool)
3. [Shift]+[Alt]+[Strg]+ (creates a new layer above the active layer)
4. [Alt]+[Backspace] (fill the new created layer with the new foreground color)

Are you able to create an action with step 3 and step 4 ?

1. (select the Eyedropper tool)
2. left mouse click with the Eyedropper tool (new foreground color from Eyedropper tool)
3. start your new created action

The same is possible with a script.

Have fun