You'd have several broad classes of disenfranchised and assimilated de-tribalized people as what happened OTL.
A slaveowner of one line of my ancestors was a prominent Upper Creek chief who fought against the United States in the War of 1812, before his battling the American government he was a slave owner in Southern Alabama. After the Upper Creeks lost the war his life was spared and he as well as many of his descendants were allowed to remain as slavers in Southern Alabama while most Upper Creek were expelled to Oklahoma.
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OTL Lower Creek who allied with the United States were able to remain in towns and neighborhoods in Escambia County as de-tribalized indians who slowly assimilated into white cultural norm before reforming a tribal government in the early 20th century as the Poarch Band of Creek Indians.
In lieu of maintained tribal/national treaty rights or reservations there could be sympathetic early leaders of statehood such as William C. C. Claiborne (first non-colonial governor of Louisiana noted for his relative empathy of Native Americans), David Holmes first governor of Mississippi (as a noted leader of peace brokering as well as non-removal), George J. F. Clarke (prominent advisor to Spanish governors and prolific businessmen who became the largest land owner in florida with some 33,000 acres that he left to his heirs; all the children of two black women one of whom he was openly married to) in East Florida, etc... a willingness to edify incoming East Coast American whites of a three caste system of White, Brown and Black.
In this ATL a treaty by newly minted governments of Alabama, Mississippi, Florida and the Florida parishes takes on a similar tone to the Adams-Onis treaty insuring freeborn peoples of the land before signing as well as their descendants would have rights above that of incoming non-white people or later freed people and/or completely similar to white settlers depending on the person and town and time period.
As well as being turpentine tappers, trappers, fishers, miners, ranchers, scouts and skilled laborers as they were in OTL in this ATL I can see the "five civilized tribes" of the South remaining on the land, intermixing amongst themselves adopting modified Cherokee scripts and speaking Mobilian Jargon all while maintaining independent schools and churches that reinforce shared identity and a separate but equal lifestyle similar to that of other free people of color.
Greater access to provide needs for incoming white settlers (of whom no small quantity would without a doubt father future Natives) I can see in less than two generations a whole slew of Lawyers, doctors, mayors and prominent folk arising. Their place in society would be critical in maintaining a level of shared power in the face of a rising enslaved black African population.
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I could also see in the areas around swamps, in mountains and generally inaccessible areas native traditionalist strongholds that make a living slave catching much like the maroons of Jamaica.
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Its possible, really just look at the histories of the remaining federally recognized tribes of the South along with the historical reality of Florida Parish Creoles, New England Native Americans and de-tribalized mixed ethnic groups such as the Houma.