Oil should be changed for sure, and yes, the gas is likely stale...but fuel maintenance mode and engine maintenance mode (assuming the car was moved around at least a little during it's 3 year tenure there) should have kept things moving and perhaps burned out some of the old gas.
My primary concern would be the battery health - if it was not plugged in regularly and it wasn't powered down into transit mode there's a good chance the battery was left in a reduced state of charge for long periods, and more concerning (again, if it wasn't left plugged in) would be that the battery cooling system would have been effectively disabled as it relies on the HV battery to operate, but of course once the HV battery gets to a certain SOC, well....it can't do it's thing anymore. Seeing as how you're in Texas that's a concern.
But, I wouldn't discount it, but I would insist on getting it fully charged and taking it for several test drives from 100% to 0% SOC to confirm that the battery is getting expected range. It's unclear to me if the dealer can really do a whole lot from a diagnostic side of things to confirm battery health, that aside.
I'd also want to drive it for a reasonable period (30 miles or so) on the engine to confirm that the long period of dormancy hasn't caused issues there either.
Tires, well....arguably 3 year old tires are not perfect, but unless they're really cracked or anything from sitting in the sun they're probably OK.
12V battery, well, again, could have suffered given as how it relies on the HV battery for charging, and that whole "left unplugged" thing. Any issues there should present fairly quickly though.
Is the price right? IMHO you're in the drivers seat from that perspective - they're likely just glad to see anyone looking at it, but I can't believe it's been there that long.