At this point it's unlikely. If enough water entered to damage the screen assembly or connectors, it's likely that the liquid contact indicators would show that the board has been exposed to water. And salt water is especially nasty. Even if the logic board is in perfect working condition, those indicators triggering basically disqualify an iPhone for simple repairs like a screen assembly replacement.
The only thing that an AASP (in your case) would provide would be a complete replacement for less than buying a new one. It would most likely be a designated replacement device that could be new or reburbished. It will come in a plain box without any of the accessories. Also - it gets tricky if the iPhone was purchased somewhere else (or gray market), as distribution is usually limited to the country in which the iPhone was supposed to be distributed. We've heard of plenty of comments here that a customer was told that an iPhone could only be serviced in a particular country.
If you're concerned with getting data off the device and you can live with Apple not providing a replacement, you might be able to pay someone to attempt a temporary repair. I can't give you any specific recommendations.