A site plan would also be interesting regarding parking spaces. So far, I only see space for one car in the garage here. How many parking spaces do you have to provide? Especially if a permanent office with customer visits is planned here?
We have the regulation that 2 parking spaces are required per single-family house; some municipalities are satisfied with 1.5 parking spaces. However, if an office with customer traffic is planned, the requirement can be considerably higher.
Also, I agree with my predecessors: I don't like the hallway on the ground floor at all. It already starts with the entrance area: this stub wall between the house entrance and the office stairway. That will be tight and not very practical. Better to plan a common, larger entrance and possibly separate the separate stairway to the office with (frosted) glass. Unnecessary space is wasted here for the additional door between the stairway and the entrance area. At least omit this connecting door; you can access the house directly upstairs, and the customers don't have to.
I don't find the living room necessarily too small/narrow now. It depends on what you intend to do there. We really just sit on the couch, read, or watch TV. I don't need much space for that. The area for children to play is in front of the stove (although I belong to the outdated generation of people who think children have children's rooms to play in and a living room does not always have to be turned into a toy landfill... but that is another topic).
But the narrow hallway with the hidden staircase, I don't like that at all; it can certainly be done better so that a "living feeling" arises already in the entrance area. This reminds me more of long corridors in a prison. Because it will also be dark there. Possibly omit the "cloakroom room," design the staircase openly, as mentioned, remove the door to the office stairway, and design the entrance area completely differently.