A Wettin marrying Maria Antonia of Austria and then inheriting the Two Sicilies and the rest if the Spanish Empire on the death of Carlos II is fairly easy to imagine; he'd be a perfectly reasonable compromise candidate, in the same way as Joseph Ferdinand was, and at least one Wettin did end up marrying an Austrian Princess a generation later.
I can't imagine a timeline that merges that with the Hanoverians (who, despite their descent from the d'Este, came from a branch that had been German since the 11th century) having anything to do with Venice, however.