This is done non-stop in Munich:
Selling a part of the property to a developer and getting apartments instead of money.
The partial sale is only to save real estate transfer tax. The unsold part of the property corresponds to the MEA of the apartments.
Or you can keep it simple and sell completely. With the money, you can then buy a finished apartment building and manage it yourself. At these amounts, the real estate transfer tax is naturally quite a lot. You just have to do your homework.
Managing a 10 million project alone, I would call a leap of faith.
Whether Plan A (with GU) or B (sale) is better depends on the circumstances and experience. Being a landlord with a larger individual property is not everyone’s cup of tea.
A backup Plan C, if the property is to be preserved at almost any price, could also be devised. However, it requires a secure income for everyone involved and a lot of time. Unfortunately, the past years were not used.