I like Cherokee!Superman, but I think my favorite is "Tewa Tales of Suspense" (I never get tired of seeing people beat the stuffing out of invaders) followed by Captain Paiute.
Over in Terramagne, my indigenous soups include the Native Alaskan superheras in "The Hand of Sedna," and they mention Katsina who is Hopi. The Iron Horses are an intertribal motorcycle gang, based on the challenges faced by people of mixed heritage. There's a glimpse of them in "Turning Leaves." Fireheart, introduced in "Glorious Accidents," is Aboriginal Canadian; he and his wife Jackie Frost (French-Canadian) have a daughter named Aurora. The super-gizmologist Thingamabob has Native American heritage but has assimilated to where the only sign of it is her appearance: copper skin and straight black hair. A fair number of other people have a trace of native ancestry, and I note it in character sheets when I know about it.