Hmm..
Actually I never thought to ask whether my country, Finland, has vegan MRE's. I never really had to play around with MRE's much because I was actually in charge of group making food, so whenever I was around, MRE's weren't needed.
But we definitely accommosated (by order) everyone's special diets. I picked up a vegan girlfriend from the army because I personally made her food every time we had to feed her company, and put in a little love note.
Never thought to question her about MRE's and while I'd love to call her to ask I don't think I have her number anymore.
I'm sure there's vegan MRES. should be. And if there aren't specially ones that fit you, you'll probably just compensated in other food. One time we made a bit of a mistake, forgot to take portion of soup away before adding allergens one girls was allergic to. We ended up sending her macaroni with some shredded salami on top. It came back untouched. (who would've guessed)