What should you do in this situation?

Your choices are correct because two rules apply here at the same time: pedestrians have priority at a marked pedestrian crossing, and you must not stop on or block a pedestrian crossing.

First, the pedestrian is about to use the zebra crossing. In Germany, as a driver you must let pedestrians cross on a marked crossing (and also anyone clearly intending to step onto it). That’s why you allow the pedestrian to cross.

Second, because the blue vehicle is turning and is still occupying the area beyond the crossing, you must wait before the crossing line. The rule of thumb is: only drive onto the crossing if you can clear it completely. If you pulled up behind the blue vehicle, you would likely end up standing on the zebra crossing and blocking it, which is not allowed and is dangerous for pedestrians.

So the correct behavior is: stop before the zebra crossing, let the pedestrian cross, and wait there until the blue vehicle has completed the turn and there is space for you to pass without blocking the crossing.