Norway is taken over by Sweden, rather than by Denmark.
Sweden (+Norway+Iceland+Greenland) looks west.
Norwegian and Icelandic fishermen and settlers start exploiting, first the Grand Banks, and then what's now eastern Canada. This happens, oh, say, by 1400
Vinland (under firm central control) grows, with sizable numbers of farmers/peasants fleeing Europe every time there's a famine. (And remember, much of Scandinavia is somewhat marginal for agriculture, especially during the Little Ice Age.) (So we have some 10-20 thousand in the New World before 1600).
By 1700, Vinland is bigger than Norway in population, and growing much faster than the rest of the country.
By 1800, none of the individual duchies in the New World are bigger than Sweden, but combined there are more 'Swedes' in the New World than in Europe. Massachusetts (OTL New England, a Swedish duchy) is as big as Edwardsland (the British colony, essentially Virginia). Ontario is smallish yet, but population is growing FAST. Erie and Michigan are established.... The formerly disputed territory of Ohio is now finally Swedish.
Iroquoia and New Netherlands serve as a helpful buffer between the Swedish duchies and the British ones.
By 1900, Sweden is one of the Great Powers, on par with Britain or France
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There, how's that?