I know I'm going to be that guy probably, but please hear me out...
*breathes in* I think we need to research parasites.
Wait! Hear me out. From what I could see, from the game, we are able to use the parasites to create special suits. One of them was a full on invisibility suit, one made fog (somehow) that messed with radios and reduced visibility to the equivalent to zero in about a hundred meter area (from what I could tell running away from enemies), and a final suit that was the equivalent to power armor. If that last one or any of the other options sound good, we need to research now whilst we have modern (Heh, 1980's modern I mean) machines, technology, and specialists. Once we're gone, that's it. And I would like to point out we have the cure for the parasite. Not to mention we have seen Code Talker and Quite rely on sunlight for most of his nutrition.
I cannot stress enough how utterly game changing in terms of economics that has if humans need a reduced amount of food to survive. It is about the closest cure to world hunger i have ever heard of. Yeah, there are clearly some problems with copious amounts of water, but I would like to point out no one was trying to use this parasite to deal with this problem.
Finally, I would like to argue that with our eminent departure from this world, we are going to miss out on the ridiculous advances of Nanobots and other future tech available. Should the end game be revealed that we're going to have to take on our counterparts from this current world in the new world, we will not be as competitive unless we research the parasite. Remember how b*llshit the soldiers on metal gear solid 4 were thanks to their enhancements. It's only with the parasites that we would remain competitive rather than obsolete.
And even if that is not the endgame, there is still the Valkuria.
Granted they're easy enough to take down surprised, but they are called weapons of mass destruction for a reason. They would stop being called that if there was a hard counter that could easily be keep up with thee women and be able to be created faster rather than the seemingly scattershot attempts at finding, recruiting, and training the valks. Yes, it's a weapons race, something we just deliberately turned away from with the nuke disarmed. But, I still think that the parasites are far more versatile and safe than nukes, and can do far more good for the world then
A normal human needs about 2000 calories a day, a soldier needs about 4000. Cut down the requirements by even a half, supplemented by natural sugar from photosynthesis? Yes please.
Also it may or may not be a cure for Diabetes, but lets not get too crazy now