As amazing as it may sound today Stalin practically was bending himself over in appeasing Hitler. Invading the Soviet Union was Hitler’s biggest strategic blunder
From what I’ve read on the subject, many of Hitler’s generals were gung-ho about invading the USSR. They viewed it as a quick victory. Only the German logisticians were pessimistic. This is one of the main reasons why Hitler would often rant about his generals stabbing him in the back. He felt misled about the supposed “easy” victory he was promised.
So, yeah, if a German-USSR alliance had gone through, then things would have been very, very different. Hitler and a lot of his generals also thought that (alliance or not), the USSR would eventually go to war with Germany and they wanted to knock them out first.
I take it that you aren't referring to the Molotov-Ribbentrop Pact, in which Hitler and Stalin did, essentially, become allies (until Barbarossa)?
What was this other "offer" of which you speak?
Regards,