[kiiski]

> It's also was never a part of the 3 monarchies of Scandinavia until the more modern use of Scandinavia for tourism.

Finland was a part of Sweden from ~1200 to 1809. Finland also still has a large Swedish minority and has Swedish as an official language. The biggest religion is Lutheran due to Swedes forcing it on people when they conquered the land. Estonia is more Orthodox.

More importantly, Finland has been co-operating with the other Nordic nations politically and economically for the ~century that it has been independent. Remember that the Nordic nations aren't just a cultural region, but they also share political, social and legal systems, have a passport union (although that overlaps with the EU nowadays) and, while they have not been able to develop any official military alliance due to Russian and American pressure, they co-operate a lot.

All in all, Estonia has some things in common with Finland, but it doesn't have much claim to being a "Nordic nation". They might be in the future, but not today.