Probably a Walther, not a Luger.
Walther P38, PP, PPK or Browning Hi-Power were the most common pistols to be carried by German pilots as far as I've ever been able to find.
Norwegian produced 1911's and Luger P08s and other pistols did make their way into Luftwaffe cockpits apparently, though. Lugers are fairly large pistols, especially in a small cockpit like that of the 190 or especially 109. Although often times German pilots didn't carry any more than a flare gun.
Actually..........IIRC, irl, German sticks did not carry a sidearm. But an officer would have a Luger, not a Walther, no?
Being an officer was not a requirement for being a combat pilot in the Luftwaffe.