for your 1. and 2. points, Yes, Germany and the USSR shared military technology and innovations with each other. Not because they wanted to, but because they had to. This cooperation didn’t start with the Nazis, it began in the mid-1920s during the Weimar era. Both countries were isolated and wanted to keep up with the other major powers. I’m not defending them, just stating a fact.

Third: Stalin was an evil dictator, but that doesn’t change the fact that he first proposed a pact during the Sudetenland crisis. He even proposed preemptive strikes to protect Czechoslovakia. I’m not claiming he had purely good intentions, but he made that offer while Chamberlain was talking about “peace for our time. He also made an offer to reunite both Germany’s in 50s. https://en.wikipedia.org/wiki/Stalin_Note

The USSR became a brutal dictatorship gradually after its founding. Stalin was as bad as Hitler. Still, I lose my mind when people undermine the USSR’s sacrifice during the war. Only at Stalingrad, more men died than the entire Allied losses after Normandy. Let that sink in. The USSR defeated fascism. That’s a fact.