[DerStahlhelm]

Not knowing if they are going to address Xandar at all in Endgame, Infinity War really sets the stage pretty perfectly for a Nova movie.

Thanos attacks Xandar to get the power stone, nearly wiping out the Nova Corps. He leaves one of his Black Order, Zorr, behind to mop up any surviving Corpsmen, as he doesn’t want them causing trouble while he gathers the rest of the stones.
What’s left of the Corps, lead by Rhomann Dey attacks Zorr’s forces. It’s a mutual slaughter and only Zorr and Dey survive.
Zorr flees to the last known destination of the Black Order: Earth. A mortally wounded Dey is in pursuit.
Abin Sur, I mean Rhomann Dey manages to follow Zorr to Earth, but is in bad shape... he’s going to die. In a last ditch act of desperation he transfers the Nova Force to a random Earthing, young Richard Rider. (Marvel might want to age him up slightly from a high schooler to somebody in their early 20s to avoid hitting the same beats as Tom Holland’s Spidey).
Richard is very confused by all of this, but luckily he is guided by the not always so helpful Xandarian World Mind, providing comic relief in the voice of its previous host, Rhomann Dey, John C. Reilly. (World Mind/Dey is sarcastic and has little patience with Rider as he figures out his new powers “What are you doing?!”)
Nova gets his shit together and defeats Zorr, because the Avengers are busy it something, The End.