Prunus virginiana has alternate leaf arrangement. When I enlarge the first pic of your mystery shrub it looks to me as though it has opposite leaf arrangement?
Edited to add from what I can see of the buds on your first image, it looks like the terminal buds may be "goose-beak" shaped which reminds me of a Viburnum. Those would have opposite leaves and at least some have fall colour, like Viburnum prunifolium and Viburnum lentago:
