I like my apple crisp to have more pieces of apples than a pie filling does but I do not see any reason why you couldn't use it. You would reduce the cooking time to cook just the topping because the pie filling is already cooked. You could also use it for the bottom of apple cobbler since it typically has a juicier bottom under the more cake like topping. You could also buy the pre-made tenderflake tart tins and fill them and bake until golden.