The midfielder is close to joining Dortmund for a reported £25 million, following in the footsteps of his older brother, Jude, who played for the German club before moving to Real Madrid.
Gabbiadini believes the Bundesliga will be a good move for Bellingham, citing its unique position between the Championship and the Premier League.
He notes that the Bundesliga offers a stepping stone for young players, with a slightly less intense atmosphere and potential financial benefits of playing abroad.
Bellingham's time at Sunderland has been well-received by Gabbiadini, who praises the young player's skills and notes that he has been very good for the club.
While Gabbiadini acknowledges that Bellingham may not be as skilled as his brother Jude, he believes that being 80% as good as his brother would still make him a very talented footballer.