It was in Spain that the Luftwaffe aka “The Condor Legion’’ got it’s best practice. It was also where the Germans realized how effective the 88mm anti tank gun worked.
Yes, but you can trace the invasion of Manchuria directly to the event that finally brought the US fully into the already ongoing war.
The Japanese learned and realized things from Manchuria that helped them conquer China. Including Unit 731. Which was scarier than any German 88.