I don't believe Sébastien Haller will be a product of Dortmund like Haaland. The quality of the two is quite different. In the 3 matches at the start of this season, Sébastien Haller has not scored or assisted. he is indeed an option in Dortmund's attack line. But at his current age, Sébastien Haller probably won't have a name as bright as Haaland.
Dortmund is indeed famous for the player business they produce with good quality. However, they always produce big names from their clubs.