Interesting list, surely. But Denmark, Sweden, Norway, New Zealand all have nice neighbors. Austria, Like Japan, is demilitarized.
It is also worth noting that Japan's military is pretty strong and healthy. They just don't go anywhere with it.
Canada has only Denmark and The US for neighbors. the last military conflict with the US ended 195 years ago.
Finland has some very interesting history vis a vis its only dangerous neighbor. Such that the dangerous neighbor left it alone. Finland is sort of like Ferdinand the bull. Just likes to smell the flowers under the cork tree, but you will regret getting in a fight with it.
Iceland is part of Denmark. Odd for Denmark to be included twice.
"Socialist" is in the eye of the beholder. The US is a great deal more socialist today than it was just six months ago. Prosperous is a different story. As noted up topic, socialist is kind of hard to measure