Dark matter/energy (you must know that those are the same by now) has been observed, it is what causes gravitational lensing. The problem is that we don’t know what dark matter/energy is made out of, because there is none near any traditional matter that we are used to.
AM not so, even ordinary mass' gravity has most influence only outside its "surface" , dark matter is not a halo but also inside an entity. (There is no gravity inside a hollow sphere, at the center of the earth, or a black hole, or inside dark matter.)
dark energy might be the eternal, all pervading energy that "appears" inside, as the universe expands into the future.