I think we should focus on one of the aspects that makes them special. Elementals, yes I know we are only half way until we would typically be able to wild shape into them but i think a fun and lore friendly buff would give the Moon Druid level appropriate Elementals to turn into without having to wait until we hit endgame content (though its been confirmed we will be going past lvl10)
I don't think we should give them full on Elementals that early but there are all kinds of weird Elementals and more obscure older Elementals to pull from like the Orglash or even simply weaker versions of existing elementals like a Fire Snake or something to the effect of a Lesser-Galeb Duhr.
From what i can find the only thing "prohibiting" something like this is that Elemental Wild Shape states you can transform into the typical four Elementals so at most it is an implied restriction but in all honestly I can't see anyone losing any sleep over Moon Druids getting more flavorful and unique Wildshapes early on that would cement their roll as the more extravagant Wildshape subclass
After all this allows Larian to use the models and animations for these Wildshapes for later encounters.