For example, French representatives were signatories to the surrenders of Germany and Japan, France had an occupation zone in Germany, and of course France has a permanent seat on the UN Security Council. But (metropolitan) France was overrun early in the war, and only rejoined the struggle after liberation. So what made France special?
If it was a matter of having a large resistance movement inspired and sometimes led by a politically powerful government in exile, why wasn't Poland treated similarly?
If it was the large colonial empire, some of which remained unoccupied, why not include the Netherlands or Belgium?
Is there another reason I'm missing? Or was there some other disqualifying factor for countries like Poland and the Netherlands?
Churchill wanted France to take part in the partition of Germany so that the efforts of maintaining West-Germany was shared by three instead of two (US and UK). Another reason was having a close ally that could help in case of a hypothetical Soviet attack on West-Germany, Churchill didn't trust the US to be able to get men and material quick enough from North America to Europe in case of a Soviet surprise attack, and thus wanted the French army to be present so that Britain would not stand alone.
The Netherlands in a quite minor way was also treated as 'victorious party', especially in the Pacific War. During the Japanese capitulation aboard the USS Missouri, the commander of the Dutch armed forces in the East - Admiral Helfrich (who succeeded Admiral Doorman, KIA, as ABDA commander) signed on behalf of the Netherlands. Helfrich even went as far as to argue that one of the Allied signatories had misplaced his signature on the Japanese-language documents of the capitulation, and it needed to be redone in full. So anyhow, the ways in which other Allied countries were included in the 'victorious party' differed quite a bit on a case-by-case basis, and was often done through very minor gestures, or major indirect concessions.
Because there was two French states, the Vichy one, and the France Libre/France Combatante created by De Gaule who managed to make governors in the African colonies switch side from Vichy to his state.
This France Combatante state, however weak, continued the fight with the Allies after mainland France was liberated.
Poland could have been in the same position, but was just abandoned to Stalin by the US and Britain.