Stair area 3.04m x 2.25m - 15 or 16 steps

Well, first you would need to know what and if anything can be changed at all. So, exact measurements and then calculate and draw. And that by someone who also knows exactly what needs to be done with stairs. Because that is not trivial.

The building permit basically applies to the building described in the applicant’s graphical explanations. The material is not important to the building authority, but I would not recommend deviating from the number and dimensions of the risers.

Well, I think that is a bit exaggerated for a single-family house. It’s not a public concert hall where people are crowding up and down the stairs. The authorities hardly care if you deviate by 10 cm here.

If I see that correctly on your floor plan, an additional step would hardly be a problem if you reverse the direction of travel. Is that still possible?

If I read your floor plan correctly, another step would hardly be a problem if you reverse the direction of travel. Is that still possible?

Yes, reversing the direction of travel would still be possible.

Can't I just add one more step before the landing? It's about 12cm by which the step extends, and it would hardly bother me. The stairwell has minimum dimensions of 3.04m x 2.25m. We won't have a problem with headaches because we won't meet the 2m headroom clearance here. See also the picture.

it would hardly bother me

Many things often do not seem bothersome. But this advanced step will be a stumbling block in the hallway, which can become dangerous for other residents in the house as well as for you.

On the ground floor at the bottom of the stairs, the step would be very unfortunate. As Yvonne already writes, it becomes a tripping hazard. It also narrows the hallway in front of the double door.
Upstairs, on the other hand, it fits in without any problems:

Of course, it might be more effort because a piece of the ceiling has to be sawed off. But better to use the saw once now than to keep stumbling over the step forever later.

PS: Please don’t always make such tiny excerpts. You always need the surroundings to assess the situation.