Das Bunderarchiv has more than 15,000 online photos of the World War 1 period, mostly in chronological order. Starting with Southwest Africa, they run through the post-war revolution, putsch, and rearmorment. Also included are aircraft and ships, including many with battle damage. Quite a bit armor and artillery, both German and allied. Few good shots of softskin vehicles, however. There are many duplicates and a lot of propaganda posters, but still worth a look. Unfortunately, I've yet to figure out how to do a selective search on a particular item (e.g., "LK-2). Take a look at https://www.bild.bundesarchiv.de/dba/de/search/?yearfrom=1910&yearto=1920&query=&page=1
I clicked on "Finden" and typed "A7V" and clicked the small mag glass icon and several images of the A7V came up. Seems like this should work for any other search.
And if you search for LKII you get several pictures of a Whippet . . .
__________________
"Sometimes things that are not true are included in Wikipedia. While at first glance that may appear like a very great problem for Wikipedia, in reality is it not. In fact, it's a good thing." - Wikipedia.