Make our new building smart

Why bother with KNX at these costs? There are alternatives like Enocean that are just as good as KNX and cost only a fraction. I would estimate about €5000 for that... And yes, it's also a standard with many manufacturers and comes from industrial automation. Accordingly, it is very reliable. If done cleverly, it hardly costs more than a conventional installation.

EnOcean is not comparable to KNX. At most for combining, but that is not necessarily required. Philips Hue has EnOcean technology in the wireless switches. There are many ways to achieve a goal. However, only KNX offers a standard and thus an open system. And in new construction, you do wired...

Enocean is also a standard. And I am not aware of anything KNX can do that cannot be done with Enocean. And whether to use wiring or not is more a matter of taste than a law of nature. I do not want to do without my mobile phone, cordless phone, satellite system, or Wi-Fi even in a new building. That means that in everyday life people rely heavily on wireless and do not depend on forced wiring. And it is not radio signals that fail, but the technology behind them. And then it does not matter whether cable or wireless is used. The conditions for good reception must of course be planned, and in reinforced concrete construction I would, of course, rather opt for cables.

And how many manufacturers really participate in the EnOcean standard? If the radio control unit from EnOcean is broken, how many alternatives from other manufacturers do you have? Depending on the construction and distance, you need repeaters. If something in the radio system is defective, (a part of) the system no longer works. With KNX wired, no problem. Depending on the scope, KNX is also cheaper. I am well acquainted with EnOcean technology. After all, I never drop such a radio switch. The energy harvesting system is very fragile to shocks. Whether it is really industrial-grade is questionable. If you build with Weberhaus or Viebrockhaus, you can use EnOcean since they offer it under their own name and certainly have some experience. I would not want to do without WiFi either, but I would never consider replacing my entire Ethernet with it. Eventually, the frequencies get crowded. And even the currently fastest available WiFi is not even half as fast as Gbit Ethernet. We are not even talking about 10Gbit. Wireless is for retrofits, low bandwidth needs, and non-critical applications. So wired in new buildings. But there are also enough people for whom a Fritzbox in the center of the house is sufficient. But that is not the target group for home automation. At most for remote control, but not smart.

There are perhaps about 50 manufacturers involved. 400-500 companies participate in the Enocean Alliance. Including well-known companies like IBM and Microsoft.
There are about 20 radio control units, although every NAS, PC, or Raspberry can be an inexpensive radio control unit. No €1000 software is needed for this.
If the mouse chews through the main distribution line, KNX is dead, Enocean keeps transmitting. You can always come up with a scenario where one breaks down but the other does not. You should also build an Enocean house redundantly so that not one component can bring everything to a halt. With Enocean you can also teach the transmitters directly to the actuators, so that even in a central unit crash, all the "simple" things like switches, dimmers, etc. continue to work. Similar to KNX.
A falling radio switch may be sensitive, but I also don't know how many KNX components survive a fall unscathed before installation. With costs of €80k I would try to avoid that. That is not a normal scenario and I hopefully only install a button every 20 years or so. It shouldn't crash in between.
As you already said, Weberhaus and Viebrockhaus build with Enocean and they are not exactly considered cheap companies that do not focus on quality. Weberhaus was recently awarded for its smart home concept. Has been relying on Enocean for 10 years now.
10 Gbit is a lot but theoretically WLAN 6 can do that too. In practice it's less of course, but just think where we were 5 - 10 years ago. Ethernet above 10 Gbit is really dead, radio is still scalable. For over 20 to 40 Gbit you will have to switch to fiber optic. But is that supposed to be a deterrent example? With WLAN 6 you can copy a 4K movie from A to B in a few seconds. Isn't that enough?
KNX is certainly top and everything is logically thought out, but the additional costs are really not to be underestimated. Not everyone wants to drive a Porsche. With €10k you can implement everything you desire with Enocean, usually €5k is enough and the KNX prices up to €80k are simply a joke.
And the retrofittability with Enocean naturally has further advantages. Who knows at the beginning what they will want and need in the house in everyday life. Which sensor has to be here or there, what sensors are there, which ones are still being developed, .... Who knows how habits will change. You get older, children come, etc. With Enocean you can retrofit sensors or additional switches and you don't even need a tool for that.

KNX
If retrofits should come, then wireless.
Christian, now you have another alternative.
Every system has advantages and disadvantages.