When I was in college in the early 1980’s, the place was rife with ‘fellow travelers’ who went far out of their way to excuse/defend/support the Soviet Union. The left at the time most definitely saw the Soviets as part of the grand progressive experiment.
I can’t tell you how many dorm room bull sessions resulted in discussions about the great Soviet system. Point out oppression, and the response would be that capitalism is oppressive, and at least in the Soviet Union everyone is equal and everyone has a job and everyone gets a good education.
I knew plenty of leftists at the time who were convinced that the Soviet model was the future. They marched in solidarity with Cuba, Nicaragua, and other Soviet puppet states. They marched against “American Imperialism” but defended Soviet aggression and expansionism as the necessary response to America or because the Soviets’ history of invasions reasonably made them want to create a buffer around themselves - this was often the excuse for the Soviet invasion of Afghanistan.
To this day, you can’t go to a left-wing march in America without seeing Soviet iconography - hammers and sickles, raised fists of the worker, Che Guevera hats and T-shirts, etc. These marches are often funded by overtly communist outfits such as Worker’s World.
As for the millions dead as the result of communism, the answer you’d get varied from, “That’s a capitalist lie” to “That was Stalinism - not communism” to “you’ve got to break some eggs to make an omelette”. This was usually followed by a grand description of just how miraculous the industrialization of the Soviet Union had been.
If you doubt the ‘progressive’ support for Stalinism or at least Soviet Communism, you just need go back and read what The Nation and The New Republic were writing at the time. Certainly there were factions within - Trotskyists vs Stalinists for example (look up the Dewey Commission for an interesting look into those times), but they were never anti-Soviet, even though this was the period of some of the worst mass murders and forced starvations in the Soviet Union, and these facts were well known at the time. The British writer who broke the story of the Ukraine Famine that killed 7 million people was sacked by the progressive Manchester Guardian because it supported Stalin.
In America, Walter Duranty (who won a Pulitzer Prize for journalism), was writing in the NY Times as a mouthpiece for the Soviets. He wasn’t an obscure writer, either - he was bureau chief in Moscow for the Times. Duranty even defended the Gulag system. How did the American progressive magazine The Nation describe Duranty’s writing? They said his articles were, “the most enlightened, dispassionate dispatches from a great nation in the making which appeared in any newspaper in the world.”
The Soviet Union - a great nation in the making. A grand progressive experiment. And hey, if you’ve got to break a few eggs to get there, so be it.
And the difference between the Communists and the Nazis was not at the time right vs left, but a split between international socialism and national socialism. Communists saw socialism as a worldwide trend, with workers uniting throughout the world against their oppressors. The Nazis were nationalists, and saw Communism as a threat to national pride and sovereignty, and to the purity of German bloodlines. But they didn’t totally disagree about socialist policy.
As you know, the actual name of the Nazis was the National Socialist German Workers’ Party. Their platform included a guaranteed job at a living wage, universal education, expanded old age security payments, creating jobs through infrastructure works, a greater share of profits from heavy industry for workers, nationalization of industries that the Reich felt were not performing in the interests of the workers, the abolition of usurious interest rates, abolition of land speculators, breaking up large organization and turning their facilities over to small worker-collective type businesses, etc.
Of course, their platform also limited this to people of the proper race, and they made no bones about the fact that they were going to enable it by punishing the ‘mongrel’ races and other undesirables. They were crazy, but it was a crazy mix of leftist ideas and insane nationalism and racism - not a mix of capitalism and insane nationalism and racism. Just to be clear.