Yes, princes from Denmark or the Vasa family were better in lines of succession. The four most fancied candidate are a Vasa prince (too young), king of Denmark (unpopular with Swedes), an Oldenburg duke (tzar Alexander brother-in-law and thus were rejected) and Duke Augustenburg, a brother of the previous dead heir.

Napoleon would picked Augustenburg. However, the Swedish Diet want a warrior-prince in the mold of Gustavus Aldophus to take back Finland from Russia, and Augustenburg is Danish. So the delegate, count Morner, they sent to ask Napoleon for consent, went rogue, and go to Napoleon and asked for his family.

Eugene, Napoleon' s stepson were also a candidate. However, his wife, a pious Catholic, were heavily against coverting to Lutheran. Eugene cannot go against his beloved wife and politely declined.

Bernadotte came next. Bernadotte captured the Swedish envoy' s uncle as war prisoner and he hyped Bernadotte up consistently. So did the the way Bernadotte managed Swedish territory endeared him to the Swede there. Being from Gascony, were fully aware that he is only Catholic because of his ancesters were forced to convert from their Hugenots faith and his mother is Hugenot. He ready to accept even if he wife don' t.

All in all, Swedish nationalist do not want more Danish or Russian influence, so they ignored the legitmate candidates and prefered to find a soldier to take back Finland from Russia.

Source:

Friedrich Wencker-Wildberg. "Bernadotte" 1936.

Edit: Found a better answer than mine here https://www.reddit.com/r/AskHistorians/comments/nyw2g5/when_the_swedish_parliament_was_looking_for_a_new/?utm_medium=android_app&utm_source=share