That Spanish Civil War;
"The Spanish Civil War was a major conflict that devastated Spain from 17 July 1936 to 1 April 1939"
But then, that wasn't WW2, even though Germany supported the nationalist Franco with their air force and other aid. I think Franco was a very wily person. Just moths later when Britain and France declared war on Germany, Spain announced its neutrality. Or more properly, was officially "non-belligerent" during WW2.
I'm not sure they can count a German killed in China in 1937 either. It is generally accepted in the West that WW2 didn't start until Sept 1939, so western nations would have considered that Japanese/Chinese conflict differently until Pearl Harbor in 1941.
I have just found a page of random facts about the war that I found most enjoyable.
I particularly liked the statistic that the first German killed in World War 2 was killed by the Japanese, in China, in 1937. I assume the German assistance to Fascist Spain hadn't started by then.
Then there's the first American killed in WW2, killed during the Winter War between Finland and Russia in 1940.
Hope you enjoy this diversion.