Survey: Which building material/construction method have you chosen?

If we were to build again, we would probably have all interior walls made with a thickness of 17.5 cm.

In what way are 11.5 cm (with KS) still too little for you?

We built with expanded clay large panels + 16 cm Styrodur insulation on the outside

Expanded clay cannot be directly equated with pumice, but it is similar enough for me to favor it for a closer choice if I were ever to move away from the pumice area. Because, mind you: I do think pumice is good, but not that the world must be saved by its nature, rather that it is a building material without long transport routes carries weight as an argument for me.

What I read about gas concrete as horror stories I cannot understand at all: my father lived multiple times and for many years in gas concrete, and "my" commercial building was also made of it – without any annoying peculiarities.

Every material needs its own plug, for aerated concrete use drive-in anchors no drilling...
or heavy-duty anchors

That is certainly correct. I can only speak for myself now, an IT person and highly unskilled in crafts, I want it to be as uncomplicated as possible and not have to think too much about which anchor I have to use. I want to use the "standard" or the fastening material that is, for example, supplied with the piece of furniture.

In what way are 11.5 cm (in calcium silicate brick) still too little for you?

I believe that an 11.5 cm wall—regardless of the material—does not provide good sound insulation. In addition, with our construction, the electrician wanted to install an outlet at the same height on both sides of a room-dividing wall. As a result, we ended up with a hole in the wall.

That is certainly true. I can only speak for myself now, IT person and highly unskilled in crafts, I want it to be as uncomplicated as possible and not have to think much about which plug I have to use. I want to use the "standard" or the fastening material that is, for example, supplied with the piece of furniture.

If it were that easy, Fischer or Hilti would only have one type of plug in their program. The most commonly supplied cheapest universal plug often works somehow, but I've also seen new TVs lying on the floor. If it has to be easy, then concrete wall!

Even the Swedish furniture store includes a note that the dowels are not suitable for all walls

It makes perfect sense to first philosophize about the dowels and then derive the necessary wall from that... if you have no other problems. You go to the hardware store, say what kind of wall you have, buy a large mixed pack of suitable dowels, and just use them... I don’t know anyone whose kitchen cabinets have fallen down, whether drywall, concrete, brick, aerated concrete, or wood...

Even the Swedish furniture store includes a note that the anchors are not suitable for all walls

That's why a wall that can handle the widest possible range of anchors is ideal.

It makes quite a bit of sense to first philosophize about the anchors, and then derive the necessary wall from that... If you have no other problems
You go to the hardware store, say what kind of wall you have, buy a large mixed pack of suitable anchors, and just use those... I don't know anyone whose kitchen cabinets have fallen down, whether KS, concrete, brick, aerated concrete or wood ...

When it comes to kitchen cabinets, I believe you immediately, because usually the kitchen is not self-assembled and the installers know exactly how to fasten something.
But I am not an installer, and with regard to simplicity, as already mentioned above, a wall that can take a wide range of fasteners is ideal.