You can either use the same photos to average them without prior star alignment – this would create star trails while reducing noise in the foreground.
And don’t worry about the blurred foreground. You can either use the same photos to average them without prior star alignment – this would create star trails while reducing noise in the foreground. Or you do what I like to do: keep your camera in place and take a nap for a few hours until end of nautical twilight and then take some long exposures to capture details in the foreground.