Well if they’re neutral then if anything I can see them copying what Spain did IOTL. Even if they do at some point join and play a decent part in ending nazi Germany I don’t think fascism will gain legitimacy. If anything we just wouldn’t lump nazism in with fascism. I highly doubt anyone would let Austria have fascists in power, after this no one will want to hear the words “Austrian” and “fascist/authoritarian” in the same sentence.How would the Fascist ideology and movement look like as a whole after WW2? This is in the event of WW2 in the event Italy is in the Allied Powers. That and I could see the rise of Fascist movements with Fascism being legitimized as the ideology that helped beat the Nazis, and the Fascists try to emphasize a difference between "Sane and Moderate" Fascism and the "Insane and Hardcore" Nazism.
For Spain, I could see Francoist Spain maintain its Falangist, Fascist and National-Syndicalist policies, unlike OTL in which Francoist Spain basically "abandoned" Fascism, sidelined the Falangists, and turned to Authoritarian National Conservative. Also I imagine Austria being an Italian buffer, with the Italian-sponsored Austrofascists being brought back to power in Austria.