It's obviously not a prequel. It's an alternative timeline where Annorax – determined to stop Janeway – deflected comets near all the non-Earth Federation planets, preventing/altering abiogenesis like Picard did in All Good Things. This led to the formation of an entirely new alpha quadrant in terms of cosmic neighbours, delayed the establishment of the Federation, and Zefram Cochrane never flew his first warp engine because La Forge wasn't there to coerce him into doing it, and we saw the transporters get replaced by good exciting and daring storylines.