The difficulty is resolution, capturing all the scales correctly from hundreds of megaparsecs down to the sizes of galaxies. The Great Attractor is a hypothetical center of attraction for the Virgo cluster. It would presumably have to be an enormous concentration of mass, far greater than average. If the Great Attractor is itself approaching something else, that implies an even larger concentration of matter. Measurements of large-scale galaxy motions is a very difficult business, so the existence of the Great Attractor remains, at present, somewhat uncertain.
People tend to think of galaxies as isolated entities but maybe they are more like coral islands.
We see the island where the coral pokes up above the reef, but the reef is continuous under the surface of the water.