Yes I think this may in fact being the case, Hitler in OTL fought in France in France and saw a country as developed or more than his homeland, that may have created much of his attitude toward the people of East Europe. If jhe fought in Poland on the other hand, suddenly his homeland would seem much more developed and advanced and at the same time he will see Poles not much different from the people of his homeland except that they are subjugated by the Tsar, while farther east they become more alien and the only civilians he can talk to are Jews. So we may see a Hitler, which leave his insane anti-semitism behind and end up seeing Jews as semi-Germans rather than subhumans, one who see Poles as slavified Germans subjugated by the Asian hordes, Russians as inferior but brave barbarians.
Fundamental we may get a Hitler, whose perspective have radical change, one which want to conquer East Europe, but not to settle, but to bring the Poles and Jews back into German.