You need to make some kind of limits to your WWII Cinderella stamps .....India fund raising ,Italy breakups due to political groups, Switzerland Soldier stamps , Hitler Head overprints ,American Military ensignors , I can give you another 50 subjects that would be included .
Yes, the topic may be too broad to be effectively done in the manner proposed. If it were just allies, axis or neutral nations cinderellas it might work. There was a great deal of philatelic propaganda produced during that time.
The closest thing I have to a WWII cinderella is a poster stamp advertising the "32a Universala Kongreso de Esperanto" in Marseille, 3-10 August 1940, which was cancelled because of the war. The congress eventually took place in Bern in 1947; I have a poster stamp for that one, too.