It should be noted that Feddit.org was included to represent Germany, Austria and Switzerland.
I did not include Baraza.africa as that was too encompassing as it covers the whole African continent.
Hopefully this post inspires more countries to join the blue club!
Misskey is, of course, very popular since it was developed by a Japanese person. I myself run a Misskey server.
Sorry, but I couldn’t find any information about plans for Misskey channels to federate with groups. Misskey’s developer is not very proactive about federation, so if this is true, that would be great to hear!