Dortmund and Leverkusen won't pose a serious threat to Bayern Munich this season, as neither team is yet on par with Bayern Munich in terms of strength. However, if we look at the details, Dortmund might be better than Leverkusen this season, although Dortmund won't be able to break Bayern Munich's dominance this season, as Munich remains quite solid with the depth of their squad. I wouldn't expect anything less from Leverkusen or Dortmund this season, as Munich will never neglect any opportunity to win this season.
Both teams have only played one game this season, but only Bayern Munich was able to win. Bayern Munich destroyed Stuttgart by scoring six goals without conceding any, while Dortmund drew with St. Pauli 3–3, Dortmund may have won the game, but they conceded a goal in the 89th minute. Perhaps they were unable to defend the three points since Filippo Mané was sent off in the 86th minute, and St. Pauli scored from a penalty.
However, I've always said that no team has the strength to compete with or pose a threat to Bayern Munich this season. Bayern Munich has spent a lot of money on top players in order to compete for any title this season. Dortmund and Leverkusen both failed to win their first games, Ten Hag set a new record at Leverkusen, after they lost their first home game of the season. Bayern Munich is going to win the title with no problem this season.