Poor ventilation

Hello everyone,

we have a bathroom in our old building from 1969 (uninsulated exterior walls) that measures only about ~3x2m.
In addition to the toilet and sink, there is also a shower.
After showering, we usually ventilate with a tilted window. However, this is not very comfortable in winter.

I am a bit afraid of mold under the suspended drywall ceiling and wonder if there is a way to ventilate the bathroom differently, for example with a fan that blows the air outside when the humidity rises significantly. However, I do not want to make a hole in the house wall.

Does anyone have an idea/tip?

In any case, it makes more sense to open the window fully rather than tilting it. When tilted, the walls around the window cool down, and water condenses there, leading to mold. During short burst ventilation (15-20 minutes), the air is completely exchanged, but the walls, ceilings, and floors still retain their heat and then warm up the cold air relatively quickly again.

How do you want to install a fan without breaking through the exterior shell anywhere? Is this property owned or are you renting?
If owned, I would search for "dezentrale Lüftung".

Thank you for the quick response. It is property and I was thinking of ventilation on the window frame or something like that.