Most plausible shattered Canada is a Dominion of Newfoundland, a Maritimes Dominion (Nova Scotia, PEI, New Brunswick), a Quebec dominion, an Ontario Dominion, and a Ruperts' Land Dominion (Prairie Provinces) plus a Columbia Dominion (BC, maybe with Washington and Oregon) which likely is sold to the United States at the behest of its significant minority of American settlers. The whole thing could go to the United States depending on political circumstances, but to keep a recognisable Canada, such a set-up would need to occur, and said Dominions would need to resist any urge to unite. The Maritimes Dominion could have an interesting issue regarding Canadian Gaelic culture/language.
Brazil OTL was held together based on the strength of the Portuguese monarchy there, but in theory, most of the provinces could have gone their separate ways and then fought over the interior. Like elsewhere in Latin America, skilled warlords could put together larger unions which might be similar to the statistical regions of Brazil. So a balkanised Brazil might have Grao-Para (basically North Brazil
, but Tocantins, Rondonia, and Acre aren't guaranteed to be part of it), the Confederation of the Equator (with the Northeast Region, plus Tocantins
), Brazil proper (with Espirito Santo, Rio de Janeiro, Minas Gerais, Sao Paulo, Goiás, Mato Grosso, and parts of Parana), and a southern Brazilian state, with coastal Parana, Santa Catarina, and Rio Grande do Sul. Powerful caudillos would dominate in the 19th century, putting together various confederations of states out of the corpse of the Portuguese Empire, before the region is able to settle down, and like elsewhere in Latin America, I expect Brazil Proper and southern Brazil to develop fastest, attract the most immigrants, and become the most prosperous countries, simply because of geography.
An earlier PoD could lead to lots of unique set-ups. Like a TL where the bandeirantes
are blunted in their expansion of Brazil, and thus leading to a Spanish Southern Brazil (maybe up to southern Sao Paulo State), which might resemble Paraguay in culture. Or the Kalmar Union returns to Vinland and colonises "Canada" where instead of English vs French being the main separation, you have Norse vs Finnish as a division thanks to the extensive use of Forest Finns the Kalmar Union might use to settle the land, so perhaps you can get a Finnish-speaking Maritimes (with a significant Norse minority as Finland OTL has) in some balkanisation of this country.