They’ve pretty openly worked constantly on issues of ecology and environmentalism/environmental racism for decades now. The turn to electoralism is a far more recent trend for the Greens.
I’d actually think the opposite - they’re the largest third party in the US - and all of the “movement for a people’s party“ has simply lead to the immediate liberal media Crucifixtion of DSA and the sloppy reintroduction of the Libertarians, whose ideologies exist from libertarian socialism to anarcho-capitalism and have never had a coherent message.
They have been around for a lifetime at this point. And while I know what they're up against, they haven't made a ton of progress and unless they're able to court some serious celebrity they will continue dog paddling and offering up policies for democrats to co-opt and water down. I don't see them being able to attract a big enough crowd or coalition to do what needs to be done.
I think you can bypass some of that loser/joke stigma, do more towards earned media and scooping up people who like green policy but aren't excited about them as a movement with a new party operating as a container for the OWS/Sandernistas at the foundation.
Unfortunately...you need celebrity. Jesse Ventura would have been the most dynamic/viable green candidate that I can think off off the top of my head and even that's kind of short of what could be done if Bernie had decided to go third party. It just seems like a conventional party that will always be seen as the hippie section of the democratic party for them to peel off and steal from.
I think we gotta go a different route.