Which smart home system is suitable for our new building?

He did not say that. However, for him, "Smart Home" is also not what we understand by it. His Smart Home is the self-driving car that finds its own way, "our" Smart Home is lane assist and distance radar with cruise control and navigation.

I am totally unsure I am trying to inquire in order to be able to decide what we should do I don’t want to end up saying I should have taken KNX or f@h because wireless is completely crap But I also don’t want to stand there having spent a lot of money on knx or f@h (which we actually shouldn’t have right now and would have to be saved elsewhere) and say yes wireless would have been enough for us

Why is it so hard for you to say what you want? How do you make other decisions about the house or how do you choose a car?

To me, it simply sounds like fomo.

Just decide for yourself whether you can realize your wishes with [Funk] and possibly live with battery changes and occasional [Funk] disruptions, and then go!

I would approach it the way I have approached most decisions.
Think about what else will be coming your way, also remember that we currently have 7.x% inflation, and then ask yourself:

How much budget do I have left for electrical/smart home without getting into trouble elsewhere.

Otherwise, in the end, you'll have to cram a kitchen costing 5,000 EUR into your beautiful smart home because the budget is exhausted.

It has to fit into your financial framework. And you can live quite well without a smart home. I know, I've been doing it for 39 years ;)

My problem is that I cannot properly assess either. I also do not know what functions we need and what is possible with radio and how big all the radio problems are. I probably do not even have an idea of what is possible with KNX and therefore cannot really estimate whether the additional cost would be worth it for us. Yes, we have already calculated a budget. You can still save something on many points.

I am totally uncertain I am trying to inquire in order to be able to decide what we should do I don’t want to end up standing there saying I should have taken knx or f@h because wireless is completely crap But I also don’t want to stand there having spent a lot of money on knx or f@h (which we actually don’t have at the moment and would have to be saved elsewhere) And say yes wireless would have been enough for us

As everyone here says, unfortunately you have to decide for yourself in the end and be able to live with the decision. But from everything I have read from you here so far, you seem to be in a very similar situation to me. My decision was to do without inflexible electricians and to forgo the money for a bus system that actually wasn’t wanted (and in fact wasn’t needed) and to retrofit with wireless. For many here in new buildings that is a no-go, but such cases simply exist. Have a look at ioBroker or openHab or HomeAssistant. Maybe you will be happier with that in the end, maybe it will drive you crazy. And if in the end you do want everything from one source, just take HomematicIP and that’s that.