Final floor plan planning - Rose-colored glasses

no sink in the office

I don't think that's a problem. So far, I have never needed a sink for washing; my dryer has a drain hose.

But for rinsing the lint filter (we even have two of them) very practical indeed...

Hmm, that's true, but I do that so rarely that I don't need an extra sink for it probably also depends on the dryer.

I would never want to have my washing machine and dryer without a [WB] nearby. Not only clean the lint filter, but also empty the condensate water. My dryer also needs the condenser cleaned from time to time. Should you then carry it halfway across the house? With heavy dirt, it can happen that I pre-clean. Either let it soak, steep, or at least (this happened quite often during the garden creation phase) wash off coarse dirt before putting the item in the washing machine for a joint bath with the other laundry. We really have a small utility room, but a [WB] was a must! In my dream utility room, I would still have space for a sewing area where the sewing machine is permanently set up and small repairs could be done quickly and easily without having to get the machine out, set it up, plug it in, thread it, sew, unplug it again, and have to pack it up and put it away—but then we would have had to give up the sauna. Better to just always get the sewing machine out separately *g*

I do that so rarely that I don't need a separate sink for it

How does that work? We have to do that after every drying process?!

I am by no means a floor plan expert, but to me it looks a bit angular, more like the much-described Tetris. Depending on what your husband plans to do in the office, a WC should also be accessible from there when dealing with customers; the one with the washing machines etc. has already been mentioned and would be an absolute no-go for me because of heat, living comfort, and noise. Is there no basement or a common room in the building, like in a typical condominium?? I would also combine the two mini bathrooms into one, even though I generally like the idea of a separate guest WC.

We had planned a hole from the office where we can throw the laundry from the bathroom.

That probably only works in theory; in practice, I have to grin when I imagine some of the situations that would arise.

When guests have to use the WC and everything is "lying around" because of the kids, I don’t like that.

Guests in the guest WC are rare, your mini bathroom is always there for you. I wouldn’t do it that way.
I don’t have an immediate idea, but I would rather steal about 2 sqm from the pantry and make a guest WC out of it, because with floor-to-ceiling shelves you can easily have a pantry on 2 sqm that can supply you with food for months (we have less than 2 sqm here, so I know).
As I said, some things also depend on whether there are basement rooms or similar.