They’re not referred to as “divinities”, you won’t see a Catholic using such language. They’re beings just like us. However, whereas a human person is a body-soul composite, an angel such as St. Michael, is a pure spirit. Also, a dead person who is now in Heaven, is simply a disembodied spirit.
In any case, both could potentially hear the prayers of non-Catholics and do whatever they could to assist so long as the request is in line with the will of God.
Since the prayers of those people who are not in the state of grace are not meritorious, God would not per se “automatically” grant the request.