Japanese pistols:
Japanese airmen used to use their money to buy western pistols, usually Ruby or Ruby-like pistols. A very popular pistol among Japanese(and Chinese, for that matter) soldiers was the Royal.
(I have no idea why the takedown lever is missing in this image)
Type 26
Possibly captured pistols, especially considering the Russians have access to C96s, like the Astra 900(C96 clone popular in China) or the Shanxi Type 17(.45 C96 clone), plus various other german or FN-made pistols gotten either through procurement orders or captured from SEA countries.
American/British/general western allies:
SAA, Walker, and Webley & Scott 1910 already mentioned
High Standard HDM, a .22 used by OSS/spy types
S&W Victory/Model 10
S&W Hand Ejector .455
.455 1911
Argentinian British Contract Ballester-Molina .45
Also, a gun I forgot to add for the general axis is the Norwegian m/1914 Kongsberg Colt, aka Pistole 657(n)
And the 9mm Spanish Star Model B
