None of which have an audience. To make a movie, you have to have at least half a chance of realizing a return on investment. Heck, half of the subjects I mentioned are marginal in that regard, yet all of them have much wider potential audience interest than anything in the above paragraph. Not trying to make it personal -- just pointing out the facts.
Unfortunately, I agree. Sometimes a good story can carry a film to success, but usually, it requires some other hook, & neither of those, though possessed of huge cinematic potential, has that hook outside the countries directly involved. A pity. However, I think there are other WW1 films which might have a chance of commercial success. Lettow-Vorbecks campaigns?
Don't worry, I didn't take your post as personal.