For the hallway, 1.50 m are available. The staircase will be 2 x 2 m. That should be enough for jackets and such. The rest goes to the basement; bike helmets go to the shed, where the bicycles will also be kept.
Although I am an amateur, it is unmistakable that this will be a structural challenge. I don't believe the builder will construct it this way. But you will still change quite a bit here, for example, your planned chimney now stands right in front of the door or in the middle of the hallway.
But what I actually want to say: I would not install a space-saving staircase. I already find it odd in a modern and open house that you allow yourself a stairwell and thus exclude the upper floor from life, but then also choose an uncomfortable space-saving staircase—I don't understand that. Without an open space, you wouldn't even be able to get Ikea packages upstairs. Then you walk through the entrance area in front of the wardrobe through the dirty zone... also not nice. The windbreak itself hardly offers space for anything. I don't see any wardrobe space in the hallway. While Kerstin wears 2–3 jackets per season, my husband has a remarkable 14 jackets, which he is not willing to keep moving all the time, since 3 jackets are just garden/work jackets, two for work, 2 for running, etc. What I want to say is that such a space should be planned for each person in a house, especially an open one. Then there are sports clothes, at least for the kids, and lots of shoes. The garage is no alternative since you don't want to put frosted things on your head or feet.
Then I would question the size of the pantry and WC: intuitively, I would make both the same size because a pantry only makes sense if you put a second freezer in it. In a 1-meter-wide room, you hardly can fit anything. However, I would rather see the pantry in the basement, where it would face better climatic conditions; instead, the ground or upper floor would benefit from a storage room for vacuum cleaners and mops. Are you planning a laundry chute? Using the staircase with a laundry basket may not be very safe.
Best regards, Yvonne