For us history pedants I’m putting together a spreadsheet detailing the historical allegiances of each Global40 territory as of June 1st in 1939, 1940, 1941 & 1942. May add December 1941 to this.
Some problems here, for example do I treat “Bessarabia” as Bessarabia proper (Romanian in 1940) or Transnistria?
Also, Poland in 1939: strict neutral or pro-Allied? Can we treat the Soviet invasion of East Poland as Stalin “activating” a friendly territory?
My Global 1940 map analysis contains dates that might be useful for your project: