Front door with or without side light

Make the door wider and integrate the window into the door. Besides a bit more light in the hallway, you will also have visual contact with visitors. I cannot see the advantage of such a narrow fixed window unit.

I would also keep the side strip. Why do you want to do without the front roof?

Yes, the hallway has no windows, only a glass door to the living room:

I feared that the best way now would be a wider door with larger windows (ornament glass).

I think then I would have to widen the door by 10 cm, would that still look good with the thick frame?

The only thing I can think of would be to box in the stairs and place the guest WC in the resulting room. Then you would have a larger wardrobe and could enlarge the door + side window.

You misunderstand, the shell is already built and windows have now been measured :) The staircase is being excavated and used as a "storage room." I only have these 2 options now, widen the door with slightly thicker frames and have a window in the door or a sidelight 15-20cm... Light will come in anyway, whether through the door or through the sidelight. Apparently, the installer’s remark was justified that the sidelight is too small to be effective and looks poor. I am partly getting this remark confirmed here in the forum.

mhh, well the openings throughout the floor plan don't really convince me.

The door to the WC should open outwards. Moving the WC is of course also an option, but it depends on the drainage pipes in the house.

The doors in the utility room should be moved away from the stair wall so that the wall can be used better; depending on the intended installations, allow 40-70cm of space behind the doors.

The kitchen, as the most important workspace in the house, is strangely underlit - otherwise, windows are used generously. Why don't you give the kitchen another window on the left side? Or at least widen the window at the top as much as possible?

I would widen the door to the living room and make it double-leaf.

I would also give the dining room a sliding door - it will be more useful there, as it will become the direct passage from the kitchen to the outside.