I didn't see anything unique about this film
Other than it being a good time capsule of the period, I didn't see how it necessarily explored the plight of Native Americans. It could have just as easily have been young lower class Whites in a small midwest town, or Blacks in the inner city.
Although not in the same documentary style as this film, the film reminded me of "The Last Picture Show" from 1971, or most of Spike Lee's films.