After 10 days CPAP was already better. It is just the mucus constantly build up and dried crusts or other residuals in the nose which cause to limit the airflow.
I noticed that sleeping without CPAP doesn't cause me the same extreme tiredness anymore (although my number of events were always on the lower end).
This part extremely surprised me, because none of the involved doctors suggested to go to the ENT (basically I went by myself) because the obstructive apnea doesn't take place in the nose but further back in your throat (therefore they never brought it up and it is not the lung's doctor specialty).
After 2 weeks I was pretty much ready again to use the CPAP daily.
I only noticed that I had to switch to a bigger cushion for the mask. Maybe my perception is wrong, but I think removing the excess tissue made my nose less "stable" if a smaller cushion rests on my nose, having less tissue leading to less structural integrity. Or maybe I just had originally a cushion which was too small.
Despite my ENT saying there was enough room in the back, I think the reduction of the turbinates helps me to breathe better at night and throughout the day. The idea to reduce the turbinates came up when I reacted well to the nose spray from the ENT which they apply to you before they send down the camera through your nose. Basically the ENT told me if Otrivin for 5 days gives you relief, then a reduction of the turbinates might help me.