Small bit of anecdata - the times when I've been most poor has been when I've eaten the most whole foods (and plant based, as I'm vegan). At those times I would nearly every day put rice and a type of bean (or variety of lentil) into the pressure cooker as my staple throughout the day. Alongside that I would have fresh fruits and steam some frozen or fresh vegetables. The biggest upfront investment was a B12 supplement, but spread over time it's cheaper than most foods.

Since I didn't have the budget for highly processed things, I inadvertently ate super clean.

So this has me thinking, there are already complex distribution channels for medicine for places in need; to that could be added a few key supplements like B12. As long as they are getting otherwise the main macronutrients met, it becomes easier for more people to eat WFPB, which in fact like me in times of poverty many people already do.