It was never proven that Thomas Jefferson fathered any children with Sally Hemings. No sample of Thomas Jefferson's DNA exists for testing and was not part of the testing. What they did was use the Y-DNA from other unbroken Jefferson male lines, none of which descend from Thomas Jefferson himself because he had only girls, most of whom died before adulthood, and compared them with Sally's descendants. What they were able to determine was that a Jefferson male did father Sally's children but they are not able to prove which one or if even multiple Jefferson males could have been the father of her children. I am not sure which of Sally's lines were used in the testing but they came to conclusions without having enough facts since the Jefferson timelines are also incomplete to determine where several of the men where during the time that some of Sally's children were conceived and there is nothing to say who could have been the father of her female children.
I think the Ancestry DNA tests can determine if you have any Native admixture but it can not determine tribal affiliations. There are several problems with this as even if Louie did had Native admixture, there is no telling how far back it was and if his parents had been so much as half Native, there wouldn't be a question as to his ethnicity. I am not sure that even with the testing we have today if it would even show up. I believe some other users who have known Native admixture in their tree are having problems with it not being reflected in their results, so this testing may or may not produce a clue. Regardless, several in my family will be testing this Christmas.
I think my best hope is to test Claiborne's descendants and see if they produce any cousin matches since they are further back in the tree.