Thank you for your assessments. We will then make an offer to Vonovia and see if they are willing to accept it. Without being rude, we will offer about 10 - 15% less than the offer made by Vonovia. Asking doesn't cost anything at first.
Of course, Vonovia does not want to sell, but we want to buy, and that is not exactly the best negotiating position. But so far, despite 2 inquiries, Vonovia has not felt the impulse to increase the ground lease.
The contract only states that we have a right of first refusal when the ground lease term expires.