Most seats Greens have ever won in any province is 3 (currently hold that in British Columbia and New Brunswick). So if Greens win in PEI, it will be first Green government in Canada and I believe second globally. They've been junior partners in many countries but I believe the German state of Baden-Wurttemberg is the only one they were actually the senior partner.
The centrist Farmers and Greens in Lithuania formed government with the Social Democrats as partners in 2016, and Iceland has a Left-Green prime minister although they aren’t the largest party.
One could argue M5S is a green party too.
