Much has been revealed about The Batman at DC FanDome, and thanks to director Matt Reeves, news about the movie's universe revealed at the event has stretched beyond the film itself and into a sister project.
During The Batman's panel at DC FanDome, Matt Reeves confirmed that a Gotham City PD series set in the same universe as the movie is in development at HBO Max. He further revealed that the series will be set in Year One of this version of Batman (The Batman will be set in Year Two) and will explore the origins of the character as he takes on the mantle for the first time:
"The idea is we go back to Year One. Year One is the beginning; it's the first appearance of this masked vigilante that starts to unsettle the city."
WHAT THIS MEANS
It was confirmed during an earlier DC FanDome panel that The Batman will take place on a separate Earth from the films set in the Justice League universe, but the announcement of this as-yet-unnamed series indicates that the movie won't quite be a standalone project. In fact, the film and series will be the first two DC projects of different mediums to directly tie into each other (beyond cameos like Ezra Miller's Flash making an appearance on the CW series).
With Reeves also revealing during the panel that The Batman will feature characters as they're just beginning to or even before they don the costumes of their iconic counterparts (such as Selina Kyle's Catwoman) it's likely that the series will show us more characters in their days of pre-herodom or villainy. The focus seems to be on the concept of larger-than-life heroes first coming to Gotham and how it affects the citizens. Given this, the police department is an interesting area to focus on since they would be the ones used to taking charge of the crime-fighting before heroes like Batman hit the scene.