The challenge: have Patagonia colonized by a Scandinavian country and have them keep Scandinavian culture until the 20th century, while the rest of South America is Spanish-Portuguese.
If they remain a colony, a dominion, something like the Commonwealth or go independent, it's up to you. It can be Danish, Swedish or Norwegian, or even have a unified Scandinavia colonize the region. Perhaps even have Scandinavians control the whole River Plate or part of it.
Is it doable?