So let's look at all the separatist movements in the USA
First of all let's look at the ones I don't think we should support
CSA, Deseret and the Northwest Territorial Imperative Their main advocates are white supremacists so yeah
Alaska Their main advocates
Second the ones I don't think would work
Republic of Lakotah(and other American Indian separatist movements) while a nation would be able to do a better job at advocating for the protection of their people a majority of American Indian people and tribe generally don't support it and would much rather work within the system of the USA
Aztlán and New Afrika I feel Chicanos and African Americans don't have enough population concentrated in specific areas for them to work
California Cascadia Guam Hawaii New England Puerto Rico Vermont?