As nobody in my household drinks white milk, I only have it on hand if a recipe specifically calls for it. And I suspect they wouldn’t quite be the same with chocolate milk, of which there is almost always a supply thanks to kids ..
Your post made me realize I'm the same way with milk. I know powdered buttermilk is considered a valid substitute for standard buttermilk when cooking. I wonder if the same is true of powdered milk.
For non-baking used it can be trickier, I believe. The powdered milk doesn't always act the same.