Some of it does not appear to be military, as it does not have military paint. Some has the same rivets used in an Electra, Earhart's plane.
Other small aircraft parts have been found on Nikumaroro, but no conclusively identified as coming from an Electra.
Natives said there was a plane on the reef in the late 1930's. The documentary discusses the tides, and water levels would have reached above waist level in an Electra cockpit. The plane wouldn't have stayed there long.
I don't believe any researchers have been to Nikumaroro in about ten years. Obviously, somebody needs to explore the water around the reef . . . unless all they want to do is sell books based on what they know so far.
Actually, they have.
A little Googling led me to the Discovery Channel website, which claims that a sexton box was found on Nikumaroro in 1940 along with the partial skeleton. The serial numbers were consistent with the type carried by Fred Noonan, Earhart’s navigator.
There may be a lot that was found in 1940 and in the expeditions from 1990 to the present that are screamingly inconsistent with Earhart, which aren’t being disclosed because they ruin a good story.
What is being told, however, paints as reasonable a picture of the place where Earhart ‘disappeared’ as any other I’ve heard.
For years, there was the story of Earhart and Noonan being buried on some island by the Japanese. Some years ago, a research team dug up those sites until they hit bedrock. They didn’t find any human remains.