Can this be used to attach to under cabinet lighting to diffuse the light better and have less strip light showing on counter

This particular film will help a slight bit, but I would recommend one of the diffuser films as they are designed for that purpose. The thinner films become fairly transparent when they are placed right on top of glass or plastic. Items directly behind the surface can be seen pretty well. https://www.decorativefilm.com/product-search?Search=diffuser