That makes perfect sense! A fictional setting with Vietnam War vibes sounds awesome. My WWII suggestion was more of a thought for the future — perhaps as a sequel or a new project after you finish your work on "Hamburger Hill." Since you already have beach landings and vehicles implemented, a Normandy-style setting down the road could be a great way to expand on your ideas and what the community suggests.
I’m really glad to hear that you liked the ideas for the equipment shop, stats, and progression! I really hope that a polished gameplay experience with these deep mechanics will attract the large audience your game deserves. Looking forward to future updates!