The offensive midfielder has established himself at Polish club Zaglebie Lubin and is now attracting attention from one of Germany's biggest clubs.
According to Ruhr Nachrichten, Dortmund have identified Regula as a player they want to monitor closely, with the teenager reportedly high on their list of targets.
Regula has already built significant senior experience despite his age, scoring 10 goals and providing eight assists in 52 competitive appearances.
His progress has now been rewarded with a first senior appearance for Poland.
Regula made his international debut in Friday's 6-0 victory over Romania, adding another significant milestone to a campaign in which his reputation has continued to grow.
Dortmund's interest comes as the midfielder develops into an increasingly important player for Zaglebie Lubin.
The German club have a long-standing reputation for recruiting young talent and developing players, and Regula's age and attacking qualities make him an obvious candidate for that approach.
The midfielder remains under contract with Zaglebie until the summer of 2028, however, meaning Dortmund would need to negotiate with the Polish club if they decide to turn their interest into a formal approach.
For now, there is no indication that a deal is imminent, but the reported level of interest suggests Dortmund are taking Regula's development seriously.
His international debut is likely to increase his profile further, particularly after Poland's emphatic victory over Romania.
Regula now has the opportunity to build on that breakthrough at international level while continuing his development in Poland.
With Dortmund reportedly placing him high on their list, the 19-year-old could have a major decision to make if the Bundesliga club follows its interest with a concrete offer.