American Oystercatchers make “divot” nests, basically a depression in the ground which in this case was a mound of shells.

While one adult sat on the nest the other paced around…

…what else is there to do until the young hatch?

I didn’t get a very good picture of the overall scene, but this gives you an idea of how vulnerable these birds are.

Marsh edge of Kiawah River, SC
June 1, 2022
Do these birds, like some others, pretend to be injured and flutter their way farther and farther from a nest on the ground to draw predators away from it?
I don’t think so, Steve, at least not the fake injury ploy like a Killdeer will do.
One of the biggest risks for shore bird nesting success is leaving the eggs uncovered in the sun which results in the egg getting cooked. So the bird on the nest knows to stay put if at all possible.
From AllAboutBirds .com:
Male and female take turns incubating the eggs, and both defend eggs and young, driving away intruders (including other oystercatchers) with calls, chases, and aggressive flight.