Here is a real original photo showing German soldiers eating pizza at their camp in the field.
Would I eat pizza at my camp in the field at a reenactment? No way in hell. You couldn’t pay me to do it! That is the exclusive province of the nightmare clown farbs.
You can find an original photo to prove absolutely anything. It doesn’t mean that absolutely anything makes sense in a reenactment context.
There is a pervasive bit of folklore that pictures of strange, oddball, exception-to-the-norm stuff will cause the heads of “stitch Nazis” to explode. That’s absurd. Everyone knows bizarre things happened, and everyone has seen lace tablecloths as snow camo, field made uniforms, all of that. I have photos of soldiers wearing ladies’ fur coats. I have a photo of German soldiers wearing sombreros. Everyone has come across stuff like this. None of this is news to anybody at all.
Being a reenactor is more than finding an original unattributed photo and doing what is depicted. It requires utilization of a broad range of sources to determine not only what is common and typical, but what specific personal expressions and exceptions were common and typical. One of the worst mistakes a reenactor can make is to select an odd item then try to look for photos to justify its use. The opposite must be true to craft a good impression: first the research, then the selection.
Unit and individual impressions are necessarily viewed through the lens of our hobby. I admire those who seek to refrain from using items that are over-represented in the hobby as a whole. Ideally, the troops at a reenactment event should be a tiny cross section of the personnel present in a real historic place and time.
Our reenactment group portrays a rear area security unit. If you look at our photos you will see a range of captured, obsolete, paramilitary and civilian items being used together with standard issue items. Every aspect of that has been researched and historical documentation guided the selection of each of those items. We use these items as part of a cohesive set of unit standards. That is the way to approach this stuff.