Balena_Rex said
True, but Mechs are already starting to be developed
For very minor drone like tasks such as moving objects through rough terrain, yes. For any sort of literal military service, no. Even on the small scale, they're obscene to support with logistics and the like, as so many moving parts means so much to repair and keep in good condition, and just tanks alone take a lot of material to keep in the field for any remotely extended period of time. Mechas aren't really feasible in the real world, and probably won't be for a long time. However this isn't a super ultra realism RP, so maybe you could start making experimental prototypes with one of the larger countries such as the not-Aztecs or another suitable country. That'd probably fit better, but it's just my opinion.
Balena_Rex said
Exo skeletons and Power suits.
These are indeed in development and the US military and contractors have light exoskeletons in the prototype stage, and since this is after WW3, I imagine they were employed during that war. However conventional fuel cells can only really support lighter exoskeletons(Like the ones the European Consolidation uses) and certainly not power armor, along with the logistical problems of keeping everything in working order.
Basically exoskeletons are certainly justifiable, just lighter variants like the ones the European Consolidation uses.