As mentioned during the conversation at Watchtower, Superman and Wonder Woman are away on a mission. The only version of Wonder Woman that has appeared in this new Tomorrowverse is of Earth-2 in the film Justice Society World War II.
John Stewart (voiced by Aldis Hodge) encounters Hawkgirl in this film. That same year, Hodge also played Hawkman in live action in 'Black Adam.'
In the popular animated 'Justice League' series, Hawkgirl and John Stewart had a romantic relationship. He also briefly dated Vixen, who also appears in this film.