Limitation of teaching the traditional ways are still the secrets of each tribe, not for viewing of the general public.
We are exposed to those who research, and write books upon the ways of different tribes, and that is about as close as you will get to being inside.
Just as we stress physical proficientcy in Aikido with spiritual balance, the same is true of most Native cultures. You must put forth an effort to have both knowledge and spiritual balance before you, the outsider, can enter their world.
I know, because I am an outsider in both worlds, having roots in both white european society, and the native culture, but not having full grasp of either until late in life.
I bring this to your attention so that you might get the knowledge available much earlier than I.
It is worth a look as much as the spiritual side of Aikido is worth a look.