Ok, first of all, thanks to everyone for the helpful answers! My floor plan has already been discussed many times (and funnily enough always criticized by the same people), so once again: I am building for myself and not for you ;-)
My wife and I are two people and will remain so, meaning the house will never be very noisy. In our current rental apartment, all the doors are basically always open (since we have cats), so we are considering leaving them out. But you have convinced me to at least keep the door from the hallway to the living room; I believe that actually makes it feel a bit more homely.
For the pantry, we planned a sliding door in front of the wall, which we will do later as our own work. It’s only a mini pantry anyway, which (hopefully) won’t look too messy.
The stairway has also been discussed many times here in the forum. My impression: either you love a stairway as a central style element (of course, suitably stylishly designed) or you hate it. There is nothing in between. It’s up to each person; we like it.
Cheers!