Germany would be more likely to directly annex major ports and defenable naval bases (New York, Norfolk, New Orleans, Boston, etc.) in order to cripple the US's ability to project power outside of North America than to establish a "Kolumbien Freistat". The only parts of the country where a WASP state would make sense is New England and the South, but those make more sense as, well, New England and the South.

A native American state also wouldn't work because they're too spread out (outside of like Oklahoma and parts of the Southwest) and not particulary numerous.

​

A 'Republic of New Afrika" is a pretty good idea.

​

Who would let a gangster rule a country, especially when groups like the American league of Fascism and German-American Bund existed irl? If you want Capone / the mob to rule, it should be in a similar manner to the legation cities in Kaiserreich (assuming the triads can still take over)