My biggest gripe about HOI4's USA is that the fascist path is what unlocks the Confederacy and that's ridiculous. The Confederacy should have been the non-aligned path, and non-aligned should have been renamed "Reactionary" because that's what they use it for, stupid meme shit about restoring empires. In America there is no monarchist tradition. There is no way that you can possibly get a native monarchism in the US by that point. The Confederacy is the closest fit for a reactionary path.
But conflating the CSA (a very decentralized federal republic based around a regional nationalism) with fascism (totalitarian authoritarian nationalism), and imagining the North would adopt it, is batshit crazy, lazy and childish. Using Confederate imagery, yes, basing the whole national identity around it, fuck no. I think they should have done the CSA as a revolter if you force desegregation, but it shouldn't have been the main US fascist faction.
Who should have been? I don't know. The Ku Klux Klan was the closest thing to a genuine successful fascist movement, it just happened to emerge and die right at the start of fascism itself. Don't know if it had any juice to come back in the 1930s. The Bund and Silver Legion and all that other nonsense were jokes. I don't think Catholic Father Coughlin could have carried the nation. I think the Business Plot was complete moonshine but it would work, sure. I think the best route would have maybe been not having an actual full-on fascist faction but instead having something like a more regular Right-wing junta headed by MacArthur or something.
That maybe would have been a good way to do the Left, too, FDR just gets his way and becomes a de facto dictator.
This goes back to the issue of start dates again. Move it a few years back and you can have Huey Long as sort of an American Peronist. Move it back to the 1920s and you can actually use things like the Klan and Blair Mountain as bases for Fascist/Communist takeovers. America's political instability and psychopathic nuttery was a 1920s thing, we'd solved it by the 1930s outside of some asshole prancing in uniforms. It was Europe that went wrong in the 1930s. But the same goes for Japan too, didn't Japanese democracy fall apart in the 1920s?
A start date in 1918/1919, if there was peacetime mechanics to go with it, lets you have enough time to plausibly set up whatever you want to. If you want to be democratic Germany, don't let the Nazis take power in the first place. If you want to be Rightist Russia then go win the Civil War. Also fuck Paradox for not including the Greens, Blacks, and Republicans in their Russia DLC the cheap hacks.