Is final construction cleaning necessary and sensible through a cleaning company?

The question will ultimately be how dirty everything is, how much time pressure you have, and whether you feel like it. I wouldn’t be thrilled to have to clean everything - possibly multiple times - if you have to be out of the old apartment a day later. Otherwise, you can definitely do it yourself...

Better have the old apartment cleaned and then you clean the house yourselves. That's how we did it and for the reasons already mentioned, it is the best solution.

I called a few cleaning companies yesterday. The 1200 euros have now become 400 euros. Whatever we do, we will definitely not book it through the construction company. Thanks for all the advice here.