And, by the way, was there ever a TL where a united Italy went explicitely after the former Venetian possessions?
Of the Western half, it certainly did; Morea, Crete, and Cyprus, if Italy seeks to and is in a position to dominate the Eastern Mediterranean, would be logical targets. The key thing is the conflict that it brings Italy into with Greece, which may be problematic, given the time Greece spent as being basically the pet country of France, Britain, and Russia.
Euboia may be pushing it, I think, Gallipoli certainly is, unless Italy has an end goal of conquering much of Greece and Turkey.