"A dark matter halo" Could this mass or gravitational impact be outside the expanding bubble of spacetime? If we are in a hole inside a block of swiss cheese,

"A dark matter halo" Could this mass or gravitational impact be outside the expanding bubble of spacetime? If we are in a hole inside a block of swiss cheese, is there a way to determine if we are seeing the effects of the surrounding "cheese"? Imagine our expanding universe to be inside a black hole. Could the "dark matter halo" be energy/matter dumped into our universe from an external source? Is the expansion of the universe actually our universe growing due to consuming its surroundings?