No Hitler Soviet Pact

WI Stalin had refused the pact with Hitler.

Would that have deterred the invasion of Poland with Hitler fearing a two frong war?

If it did not would Poland have lasted longer in one front war?

If other things happened as in OTL would the Nazis being that much nearer Moscow have had awful consequences in 1941?

If there was no Nazi-Soviet Pact, I think the Nazis being as successful as they were pre-Barbarossa is doubtful.

Remember, the Soviets supplied oil and grain to the Nazis, thus preventing a replay of the WWI British blockade. The Soviets also allowed the Nazis to use bases on the Baltic for naval purposes (though how useful they were is beyond me).

Assuming Hitler invades Poland and the Western Allies declare war, the British might try for a replay of the WWI blockade. However, I don't know how much time it will require to cause mass starvation, since the Germans will loose the Blitzkrieg soon and that'll make the blockade something of a moot point.

Thing is, with no Nazi-Soviet Pact, what will the Soviets do vis a vis the Baltic states and Finland? The Pact gave them a free hand there, and the Germans provided a very good distraction for the Western Allies.

The USSR and Great Britain between them were able to blockade Germany from all oil except Rumania, and Rumania was part of the alliance against Germany until the Western European establishment betrayed Czechoslovakia and they decided appeasing Germany was the way to go.
Without Russsia, Germany is not going to start a war with Poland. The political results of invading Poland would cause the governments of Western Europe to fall to socialists if they did not unite against Germany. Then the Socialists in France and Britain would allow Russia to occupy Germany while they tied down half the German army watching their armies on the Rhine. If the Germans removed the army to fight the Russians, they would have occupied the Rhineland and bombed and shelled the Ruhr.
Stalin made a mistake. He thought that the Western European establishment was joining with Hitler to attack him. This was right, but his decision to allow Germany to conquer western Poland and southern Lithuania, and then France, the Netherlands, Belgium, Norway, Denmark, and Luxemburg as well as keep the Czechoslovakian territories ceded by the Western European establishment during their German alliance before the Soviet alliance was a serious mistake.
He should have attacked Germany in May of 1940 when they were fighting in the west. It would have been hard for the western European establishment to change sides in the middle of an attack on them by Germany.