If you really want to Poland-wank it, you would need Germany not to fold so quickly. Perhaps a later US entry so that German relies more and more on Poland and Romania to defend the East, as they have to throw everything and the kitchen counter at the Wallies. Perhaps German wins a surprise victory in late 1943 due to superior tanks, local air superiority, and much of their industry greatly subsidized by the East in which it cannot be bombed.
Perhaps, 1944 is a bloody stalemate where US interest is waning, Germany is running out of men and employing Ukrainian mercenaries in increasing numbers, and France loses the will to continue fighting. Perhaps, in a diplomatic coup, the Wallies get Romania and Poland to switch sides in early 1945 to bring a swifter end to the war.
At this point, Germany has a mere half-million men garrisoning in the East, supported by 250,000 ethnic volunteers. They barely can fight the partisans stretching from the Urals. Romania's standing army is over 1.5 million men, and Poland's 3 million. When the tables are turned, the German reserves simply are not enough to stop 2 million Poles and Romanians, with a small Ukrainian contingent joining in on the fly in the Crimean Peninsula, from disarming the Germans in the East, while 1.5 million Poles quickly cut off German reserves situated close to the Polish border (which have almost no heavy equipment, the vast majority of which are defending German soil in the west.) Germany's reserve army could at best prevent Berlin from falling on the march, but little else. A general collapse occurs where the Germans are pushed to the Rhine and the have lost all of East Prussia. Within 4 months, the Poles take Berlin, Romania reaches Vienna, and western forces begin meeting their new eastern allies.
The result is Poland annexes East Prussia and German occupied territories in Russia. Romania gets to keep Hungary and Yugoslavia, as well as parts of Ukraine they were already given (i.e. Odessa. Sevestapol is made an open city to be shared between Romania and Poland.)
Germany is then split up into four different zones of occupation (Poland, US, France, and Britain) while Berlin is split into five (including Romania.)
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Germany was a tough nut to crack OTL with the USSR. Without the USSR, it can easily become a massive bloodbath to the west of WW1 proportions, so with the right luck and strategy perhaps they can force the Wallies to either give up, or in a diplomatic coup, get Germany's allies to switch sides.
At least this way the Polish flag flies over both Moscow and Berlin
