The reason I assume Poland could've been an antagonist is because 1920s and 1930s Germany was a second rate power anyway that with its disjointed government squandered its industrial capacity and was a medium sized country sucidally bent on the impossible task of conquering the whole of Eurasia surrounded entirely by enemies, in a series of daring medium sized strategic campaigns with no real continental or global strategic goal, when its land military was still largely dependable on horses and frighteningly limited oil reserves.
If Germany had collapsed in 1920s or 1930s, with no leadership left over, there is a good chance that Poland may have made more of a nuisance of itself and had sufficient enough military to attempt the annexation Eastern Germany and the pocket of Prussian territory on the Baltic coast, and even Czechoslovakia, but that would be as far as they'd go with what was left of Germany, a token force from France, and the rolling Soviet Union easily able to quash Poland as easily as Poland fell in OTL.
If Germany had collapsed in 1920s or 1930s, with no leadership left over, there is a good chance that Poland may have made more of a nuisance of itself and had sufficient enough military to attempt the annexation Eastern Germany and the pocket of Prussian territory on the Baltic coast, and even Czechoslovakia, but that would be as far as they'd go with what was left of Germany, a token force from France, and the rolling Soviet Union easily able to quash Poland as easily as Poland fell in OTL.