the important part is to remember that Yoko Taro is either a genius, a madman, or a troll and he has no problem putting critical plot details in other forms of media that a person playing just one of the games may never know about
dark apocalypse did further entwine the Drakengard and Nier universes via the Seed of Destruction which doesn't come up in Automata at all but is a big deal in Drakengard
Drakengard 3 had a character that was revealed to be an android but exactly how an android existed in Drakengard's more medieval/fantasy setting was not fully explained
so atm it could just be a side story but later it could be an essential plot point in a Drakengard 4 or an Automata 2
only Yoko Taro knows