Are there any aftermarket headunits compatible?

You should be able to. Theres companies out there right now offering direct fit units for almost any car. Its a bit pricey but its literally a direct fit. It even keeps all the OEM buttons, knobs, switches in the same place. Not sure if they made one for this but try searching online and see what you find.

I wonder if it would be a better option to just go get the optional headunit that the dealership carries. If they do have a better one than the standard one.

Ok so from what Ive been able to search up so far Metra pretty much makes an install kit for almost any car. Plus they also make sure that all your stock buttons and controls are still useable. So I can actually get almost any aftermarket head unit and use the Metra install kit and brackets and still have a somewhat OEM looking center console.

i have buddies that work for car audio shops and they all use metra kits to install aftermarket radios on cars. fitment is almost perfect and price is pretty good. only complaint ive ever heard is that some of the metra kits are easy to break if youre not careful.