I'm not at all sure if we need yet another undoing of the comic's ambiguous ending, but the trailer is out and it seems to be a sequel.
https://www.digitalspy.com/tv/ustv/a27408914/watchmen-tv-show-hbo-trailer-when-set/
https://www.digitalspy.com/tv/ustv/a27408914/watchmen-tv-show-hbo-trailer-when-set/