Hi! I think I said the opposite about budget (it doesn't make substantial changes to one), though it's a common false trope that going vegan is expensive so I can understand why you'd be on the lookout for it.

Re: geographical variation, yes of course, which is one of the valuable parts of looking for material grounding. A bombed out place with food insecurity may both prevent a vegan from avoiding animal products to survive and will impact what people will focus on and prioritize. I don't think it's coincidental that the modern movement of veganism emerged and took off in the imperial core where food is subsidized without being undermined by imperialism and workers, on average, receive a greater level of purchasing power for their labor than those in imperialized countries (due to imperialism).

For warm clothes, the possibility of making that devoid of animal products preceded veganism by a long period of time. Waxed canvas clothing was popular among those with access to it (sailors, those who worked outdoors in cold and wet conditions) and thick cotton garments like flannels (which didn't always have wool) were similarly popular. Both were only made popular through changes in production, of course, but they were fairly popular hundreds of years ago in parys of the world. But if you were in the far north and could not import cotton and oil, these were not options.

Re: food security, that looks like a nice project! My thinking on food security was that its increase promotes veganism itself, it is a material basis for veganism even if the security itself is not explicitly vegan. Most vegans are converts, they started out non-vegan with non-vegan parents and became exposed to and convinced by materials against consuming animal products. I think the propensity to be convinced would be positively impacted by the relative availability of food, and particularly vegan food, so that it can be thought of as a consumption choice among others.