Perhaps a tl could be imagined where a branch of the hohenzollerns settles in France in the 15th century, perhaps inherits one of the greater duchies and then from that base they wind up inheriting the throne of France in the 17th century or something.
Then on the extinction of their German cousins, the Hohenzollern king of France attempts to claim the electorate of brandenburg- or actually potentially the French branch gets ducal Prussia and manages to use that to get a cadet branch installed in Poland.
i think there was a thread about a xvii century extinction of the Bourbons that could be useful.
aiui, the remaining Capets were deemed too low status to be considered princes du sang and were not included in the line of succession, so there should be enough room for other candidates to present their claims.
house Lorraine had been included in the line of succession w/ the treaty of Montmartre, so you could have an Hohenzollern candidate for the french throne by having a branch of the family take the place of Lorraine
alternatively there's the Hugh Capet route of getting elected, but i'm not sure how to set up a scenario for it