The movie "The Crossing" serves as an official prologue to Alien: Covenant, shedding light on the fate of Dr. Elizabeth Shaw and the synthetic David after the events of Prometheus.
Alien: Covenant - Prologue: The Crossing
In the aftermath of their harrowing encounter with the alien creature, Dr. Elizabeth Shaw tends to the damaged David on a desolate Engineer spacecraft as they press on in their quest to uncover the truth about humanity's origins.