https://www.culturalsurvival.org
Cultural Survival is an example of an organization working towards pan-indigenous respect, recognition, and reconciliation. Their approach is to make changes through advocacy, media, grants, radio shows, and are funded through a combination of donations and the sale of goods directly from artists or fair trade vendors. They also publish a quarterly magazine featuring a variety of articles and opinion pieces and covering a wide variety of issues. I could definitely see teachers or school libraries benefitting from a subscription. The website also has a mailing list for news and events.
https://www.culturalsurvival.org/issues
The issues page covers their perspective on the common experiences and perspectives of indigenous groups around the world. It acknowledges that while there are massive differences in language, colonial experience, and geographical distribution, indigenous peoples nonetheless can benefit from using common political action through legally available mechanisms, communication strategies in order to amplify their voices, and approaches to dealing with extractive industries.
https://www.culturalsurvival.org/about
Finally, the About page explains that the organization is made up of a diverse board of directors and staff, including indigenous individuals. It is worth nothing that they are not an exclusively indigenous organization, and explain frequently on their website that they work primarily by partnering with indigenous communities.