The big problem with American fascism (before WWII) is that the United States is a very diverse place compared to Italy or Germany. There's so many different (European) ethnic groups, there's a massive amount of Catholics (who have been there since the 17th century), and there's a massive diversity of Protestants too.
It should be noted Germany was pretty religiously divided, with the 1937 borders being about one third Catholic and then the Pre-September, 1939 borders being about 50/50 with Protestants.
Fascism is not necessarily a racist ideology. Fascist Italy was not a particularly racist state, not much moreso than other colonial empires were (although during WWII it got much worse as Nazi influence seeped into Italy). They certainly discriminated against their Slavic population, but it wasn't for the same reason the Nazis discriminated against the Slavs. Eugenics is definitely not a trait of fascism, given it was advocated by people on every part of the political spectrum until the Nazis took eugenics to its logical conclusion.
"Race? It is a feeling, not a reality. Ninety-five per cent, at least. Nothing will ever make me believe that biologically pure races can be shown to exist today.… National pride has no need of the delirium of race." - Mussolini, 1932.
Adding to this,
with all quotes from the Last Will and Testament of Adolf Hitler:
"The white races did, of course, give some things to the natives, and they were the worst gifts that they could possibly have made, those plagues of our own modern world-materialism, fanaticism, alcoholism and syphilis. For the rest, since these peoples possessed qualities of their own which were superior to anything we could offer them, they have remained essentially unchanged. Where imposition by force was attempted, the results were even more disastrous, and common sense, realizing the futility of such measures, should preclude any recourse to their introduction. One solitary success must be conceded to the colonizers: everywhere they have succeeded in arousing hatred, a hatred that urges these peoples, awakened from their slumbers by us, to rise and drive us out. Indeed, it looks almost as though they had awakened solely and simply for that purpose! Can anyone assert that colonization has increased the number of Christians in the world? Where are those conversions en masse which mark the success of Islam? Here and there one finds isolated islets of Christians, Christians in name, that is, rather than by conviction; and that is the sum total of the successes of this magnificent Christian religion, the guardian of supreme Truth! Taking everything into consideration, Europe's policy of colonization has ended in a complete failure." - February 7th, 1945
"In saying this, I promise you I am quite free of all racial hatred. It is, in any case, undesirable that one race should mix with other races. Except for a few gratuitous successes, which I am prepared to admit, systematic cross-breeding has never produced good results. Its desire to remain racially pure is a proof of the vitality and good health of a race. Pride in one's own race—and that does not imply contempt for other races—is also a normal and healthy sentiment. I have never regarded the Chinese or the Japanese as being inferior to ourselves. They belong to ancient civilizations, and I admit freely that their past history is superior to our own. They have the right to be proud of their past, just as we have the right to be proud of the civilisation to which we belong. Indeed, I believe the more steadfast the Chinese and the Japanese remain in their pride of race, the easier I shall find it to get on with them." - February 13th, 1945
"The peoples of Islam will always be closer to us than, for example, France." - April 2nd, 1945
Now, with regards to the American aspect, I think
George Lincoln Rockwell's ties with the Nation of Islam should serve as a bias for speculation, given how that was a more uniquely American movement compared to previous ones like the Bund.