Forigite

I assume it would refer to native peoples of both Americas; Reta Vortaro says simply "Ameriko", without limiting it to North America.

We don't tend to distinguish in English, either. For example, the Smithsonian National Museum of the American Indian also covers both Americas (brief advertisement for anyone intending to visit Washington DC: its wonderful Mitsitam Native Foods Cafe also specializes in serving foods from native peoples all over the Americas)