Islanders Beach Park on Hilton Head Island has a nice ramp to the beach. This is a public park that is on the north end of the island. There are many places to stay, many with either first-floor apartments, or ones with elevators. We stayed at Island Club, on the first floor. Our resort had 4 boardwalks to the ocean, two of which were ramps. We’re able-bodied, so the slight step into the shower wasn’t a problem. (Note, we didn’t ask for a shower without the several inch barrier to keep the water from getting out.)
We stayed at Island Club Hilton Head resort which had four walkways to the beach, two of which were ramps. 
We didn’t stay in a wheelchair-accessible apartment, just a first floor one. So, some of what we found inside our apartment could well be because it wasn’t designed to be accessible.
We stayed in a first floor apartment. There was an elevator in each building to get to higher levels.
The entry has a small bump.
Bathroom has a rain spout and a moveable shower head. It has a several inch step at the bottom.
Condo access isn’t bad, but there’s a big step to get onto the patio. (Again, we weren’t in a unit that was advertised as being wheelchair accessible.)
And, the reason to come to Hilton Head Island–sunrise and the beach.
