Yes. The pilot was titled "Love and the Happy Days" and featured Richie, Potsy, Howard, Marion, Joanie, and Chuck. Howard, Joanie, and Chuck were all played by different actors than they would be on the show.
I've read that the pilot was originally to be titled New Family in Town, before it aired as part of Love, American Style. I've read that creator Gary Marshall had once been quoted as referring to Love, American Style as a showcase for unsold pilots. So has Love, American Style spun-off any other TV shows?
One episode from the second season of Happy Days includes clips from the pilot. In the pilot, the Cunninghams become the first family in town to own a TV set, and Richie gets a girlfriend who was really only interested in watching TV. That same girlfriend appeared in the season two episode, where she and Richie got back together, but then Richie wanted to break up with her as she started becoming a bit obsessive.