It's true that it's about totalitarianism to some extent. But we have Orwell's actual words here that it's chiefly about communism

> [Nineteen Eighty-Four] was based chiefly on communism, because that is the dominant form of totalitarianism, but I was trying chiefly to imagine what communism would be like if it were firmly rooted in the English speaking countries, and was no longer a mere extension of the Russian Foreign Office.

And of course Animal Farm is only about communism (as opposed to communism + fascism). And the lesser known Homage to Catalonia depicts the communist suppression of other socialist groups.

By all this I just mean to say when you're reading Nineteen Eighty-Four what he's describing is barely a fictionalization of what was already going on in the Soviet Union. There's just not a lot in the book that is specifically Nazi or Fascist.

I don't have any opinion on whether he thought there were non-totalitarian forms of communism.