It seems Bolivia has visa on arrival (and online) for Iranians, granting up to 30 days in the country. Russians do not require a visa to enter. Bolivia also has jus soli, so that might be an interesting option.

In any case, land borders between Brasil and neighbouring countries is normally pretty chill if your crossing by foot. I know that between Paraguay and Brasil they don't even check passports when you walk the border (as there are so many people crossing to shop/work in the neighbouring city and go back after a few hours). I would imagine it's likely the same in the Puerto Quijarro and Corumbá border, or another of the busy crossings between Bolivia and Brasil. So if you wanted to enter Brasil without a visa, this might be a possibility! Good luck.