Dark matter in the "standard" cosmological models is collisionless. Baryons are not dark matter in this sense. Very dim, and very hard to see, especially if they are at a temperature and density where they do not emit much detectable radiation, but they are not, as cosmologists understand, dark matter.

However some cosmologists (Ben Moore is one) write papers on collisional, strongly self-interacting dark matter. It seems to have dropped out of fashion in the last ten years though