I'd like to raise a few points:

1. Conservatives are media illiterate.
2. Deeply online groypers live under 16 layers of irony at all times.
3. Fascists love pretending that they're actually heroes fighting the real fascists who want to give people free bread. To a lot of Americans, communist and fascist are the same word.

I can't tell you if bella ciao is a popular alt-right meme because I don't hang out with them, but I can tell you it's far from impossible.