There's no "splitting the neoliberal vote" in Germany. Not only are all the other parties neoliberals too, but Germany has a parliamentary system where what happens is that parties will enter into coalition to achieve a majority needed to govern, so giving the Greens votes just makes them more likely to end up in a government coalition. And this has absolutely disastrous results as we have seen with the current SPD-Greens government.
Green parties may be different in other countries but in Germany the current incarnation of the Green party are absolute lunatics.