Nordic happiness is available to other nations

Skimming: The Nordic Exceptionalism: What Explains Why the Nordic Countries Are Constantly Among the Happiest in the World, chapter 7 of the World Happiness Report 2020.

Thus, there seems to be no secret sauce specific to Nordic happiness that is unavailable to others. There is rather a more general recipe for creating highly satisfied citizens: Ensure that state institutions are of high quality, non-corrupt, able to deliver what they promise, and generous in taking care of citizens in various adversities.

Getting there means escaping a “vicious cycle” of low trust/low participation: 

Thus, institutionally, building a government that is trustworthy and functions well, and culturally, building a sense of community and unity among the citizens are the most crucial steps towards a society where people are happy. While the Nordic countries took their own particular paths to their current welfare state model, each country must follow its own path.