I was involved in the Green Party here in Canada for a while, though I eventually had to leave because they completely succumbed to CT, but I noticed quite an interesting progression there.
For many years, it was clearly focused on environmental issues, and also had the interesting element of drawing from both the political right and left in their policy thinking. They brought quite a few people together around environmental policy who came from different parts of the political spectrum, and early on some of the best legislation around environmental issues we had was from the Conservative Party.
Over the years though they really focused on getting more and more people elected, and appealing to voters, which was natural. But it seemed to mean targeting a more specific demographic, basically progressive people who wanted typical policies like universal childcare, legal prostitution, and appealing more and more to identity politics thinking.
What I found interesting is that this has been successful to some extent at giving them more votes, if not more MPs. But I think there is a real limit on the appeal, they've now pigenholed themselves and associated their environmental concerns strongly with a very specific political ideology that many will never be on board with.