I don’t think it makes sense to do very much. Obviously where possible if it’s relevant to the software being developed, promote environmentally friendly practices. Choose service providers committed to the environment (do those exist?). There are certainly things like Bitcoin which have some very serious ethical concerns as they depend on enormous computation, those should probably be avoided (I say probably because I’d imagine it’s more complicated than I make it seem).

I would compare it to something like racism or homophobia. Obviously you won’t let people contribute or be involved in your community or give them custom if they are homophobic or racist, but you also won’t prevent them from using your software…