That sounds useful indeed! Any ideas where that button should be placed?
I would think to the left or the right of the zoom slider at the top (as the current pixel position under the mouse is displayed to the right of it). On the right would make it within reasonable eyesight of the pixel position.
Though I'm not an UI/UX designer so I can't exactly say what would be best. ¯\_(ツ)_/¯
As an user, I'm okay with any place as long as it's always visible regardless of tool selected (just like the zoom slider is always visible, because the top bar is).