It is not possible for Poland to defeat Russia without cheating. Hence your tilde key must be well used in order to provide manpower, war support, stability, weapons and fuel.
no, the soviets+france+czech+yugoslavia+romania were at war with italy+uk+japan+china, so their forces were split in between balkans(actually hard into itally) and china. The polish border was almost completely unguarded.
This is a screenshot from that war, the europe theater. As you can see, fascist UK and fascist Italy conquered france easily. Meanwhile, Poland(me) who already conquered estonia and latvia, allied with German empire and turkey(all non-aligned) calmly divided greece and Lithuania among ourselves. The date is 1939.
After that, I also gobbled italy. Then it was easy to justify war on soviet union-it only took 20 days. I, with little support from Germany, marched into unguarded territory of soviet union virtually unopposed. It was December 1940. Soviet union capitulated in April 1941. By the time any resistance started showing up, Moscow and leningrad were already mine.
Here is the state of being from beginning of war. As you can see, there are more troops on czech border than soviet border.