I checked "Soviet total victory."
Even Hitler was not so impetuously overconfident as to assume that the Reich would in fact break Soviet military power without first acquiring the resources of all continental Europe!
Russia, under Soviet power or before or I assume today, has the strategic advantage of depth, and part of Stalin's rather terrible and inefficient, but as it turned out effective, industrial development strategy was to locate key industries far to the east, beyond the Urals.
There is every reason to credit Hitler with strategic surprise achieved via the Berlin-Moscow pact. When the Nazis took over in Germany in 1933, the Soviet Union made overtures of cooperation; after all in the previous decade, the German military had secretly and illegally, per the Versailles Treaty, made deals with the Soviets to run war games and test technology on Soviet soil, hidden from the Versailles enforcer powers. The odd couple of German reaction and the USSR had precedent in other words. But in those early days, Hitler completely rebuffed any hint of cooperation with the Communist giant and Soviet policy was subsequently geared to the assumption Hitler would attack someday. By 1939, Litvinov's foreign policy initiatives seeking a common front with the liberal great powers to contain the Reich had failed. Without Hitler suddenly out of a blue sky offering the cooperation that Stalin had sought and been refused six years previously, the Red Army would be an alert, and Soviet intelligence would surely observe signs of Polish-Reich cooperation and interpret it as a possible plan to attack. As things were instead, Hitler's OTL scheme paid off brilliantly for him; it moved the Entente allies from distaste for the Soviets to outright outrage and contempt; it made the conquest of part of Poland that much easier for the Germans, giving the Wehrmacht and Luftwaffe valuable seasoning in real war conditions (other than pitifully easy operations against a disarmed and dismembered Czechoslovakia, the only German forces with a whiff of fighting since the Great War were those involved in the Spanish Civil War, and for most 1939 German forces the attack on Poland was their first taste of real combat, those who were not Great War veterans anyway, and no one had experience with the package of modern weapons the General Staff had accumulated in the interim, again beyond SCW experience) without too much risk. It secured the German eastern rear allowing Hitler to systematically carry out his plan of piecemeal conquest of the west, starting with Scandinavia, then the Low Countries, then France itself. Ignoring the value of Poland and Norway and Denmark (indeed Norway over the course of the war was something of a drain on forces who might have been of more value elsewhere) the industries and agriculture of the Netherlands, Belgium and most of all of course France permitted Hitler to greatly multiply the force he could throw against the Soviets. And in fact he did take Stalin by surprise. It is a fact that Stalin got many warnings of Barbarossa, from Soviet agents as well as from the British, but the problem was that Stalin had gotten many such warnings in the past. Mind, the biggest problem was that Stalin had a strong will to believe he had made a deal with Hitler that would last, that with another ruthless dictator like Hitler he was dealing with someone whom the Soviet Union could do business. We should also not forget that part of the Pact was the Soviets agreeing to deliver great quantities of resources the Germans valued very highly, none of which were available to Hitler in summer and fall of 1939.
So--the Reich forces, even augmented by everything Poland could supplement them with, would be far weaker than those that carried out Barbarossa OTL. The Red Army would be far less liable to be caught flat-footed. The Luftwaffe would not be permitted, as Stalin permitted OTL, to fly scouting missions in advance--OTL Stalin was afraid of provoking the Germans and tolerated a great deal from them that would not be tolerated if the Reich were assumed to be the implacable foe preparing to attack it was assumed to be prior to Hitler's kind offer of alliance.
Now of course the Red Army was also deranged by purges, and lacking the benefit of the two years of technological upgrades and general preparation 1939-late spring 1941 afforded them.
We know from OTL that the Soviet Union was able to absorb the terrible blow of Barbarossa in full brutality, and lose pretty much all of old Russia most of the way to the Urals and Caspian Sea. Much is made of Lend-Lease aid to the USSR, but a simple fact about Lend-Lease is that while ultimate delivery was of staggeringly high levels of resources, it took time to get going, and most of the mass of aid was delivered in the last years of the war. Whereas the battle of Stalingrad represents the great turning point, after which the Wehrmacht would be on the back foot and collapsing in retreat before a rising Soviet onslaught. By the time of Stalingrad, the USSR had received only a small fraction of the total aid they would later get.
So I believe there is no way a German-Polish strike would penetrate as deeply, meaning the ATL USSR would retain more resources, against a fundamentally weaker Axis force doomed to be checked earlier, farther west, and then shoved back to the prewar Polish border and beyond.
Would Stalin try to negotiate a Brest-Litovsk style concession to the Germans, if there were no prospect of any aid from any Western power whatsoever?
I really think not!