Actually in Central America and in Spanish South America splintering is already at almost maximum levels except for maybe splitting outstate Argentina from Buenos Aries and vicinity. Fewer states instead of more would be more likely given some butterflies. Splintering Brazil is difficult without multiple colonial powers dividing it pre-independence. Although a Federal State it makes sense as a coherent whole. Mexico, with its federalism vs centralism history, could reasonably split into the Yucatan, Mexico, a state based on Monterrey, and a northwestern desert state. However, there are infinite possibilities for additional splits north of the Rio Grande depending on the POD. Having the entire extent of America north of the Rio Grande consolidated into only 2 states is the unlikely outcome. A more divided North America could happen with a closer balance of indigenous vs colonial states, more diverse lasting colonization of the continent by multiple powers, or the collapse of Anglophone NA into multiple geographic entities (say like the 9 Nations on NA trope, although those divisions only make sense culturally, not as the basis for actual countries).
Brazil had Grao Para and Rio Grande do Sul. There might be other conceivable divisions for Brazil, if it gained independence in as violent (or more?) circumstance as Spanish America. Central America could still have Los Altos, another breakaway republic, as well as the Miskito Coast and the Bay Islands as I mentioned, both of which would be more Caribbean in culture like Belize. Anglophone North America has too many chances to stay coherent--you'd need some way to get more colonisers, i.e., France doing it the British way or something. Older PODs of course allow for more diversity.
Indigenous states seems very cliche. North of Mesoamerica, I don't reasonably see any indigenous states able to survive that could honestly be called an indigenous state without butterflying away Euro colonialism or at least strongly limiting it. I think the examples of Hawaii and Fiji show what the logical result might be, even if it is preferable than OTL. That goes x1000 for any Plains Indian nation, which are pretty much anarchistic by culture and any attempt to make them into a western nation would pretty much result in their self-destruction and conquest. Unless anarchist "states" become huge in the Americas.