A pinky is not to small for a western hognose, even an adult will eat one if you let them.
Maybe try putting it in something like a brown paper lunch sack, plastic shoe box, or cardboard box with the mouse and leave it alone for a while. If it won't take the f/t mouse then maybe try a small live pinky.
Westerns sometimes need the see something moveing (either the mouse or something by the mouse) to realize that it is food.
It's ok to dig them up out of the substrate to get them out to be fed. When I dig mine out, some of them will instantly start going to and trying to bite anything that moves (usually that's my hand)