Switch / Button / Double Button / Dimmer / Eltako

Thank you! Then I'm curious to see if my electrician can implement that.

Hello , I have to come back to this again. You have already helped me a lot, but I would like to briefly summarize the whole thing again and ask if I have understood it correctly now (since I don’t have 100 posts yet, I can’t have a private conversation): So. We have laid Nym 3 x 2.5 cables and want to dim ceiling spots using a double rocker switch. The ELTAKOs do not fit in the flush-mounted box. There is enough space on the OSB/plasterboard ceiling. We can now simply install the Eltakos in front of the ceiling spots with your "circuit diagram"/"drawing" and then the whole thing should work? A remark from another electrician (to whom I explained the whole thing by phone) was that we would not have continuous power which we would need (however, he did not see your drawing). Have I understood that correctly? Or could you summarize the whole thing once again very simply for me? It would really help us a lot! Of course, other answers are also welcome.

Now, the Eltakos need continuous power. You should clarify that once again. At which point this is available for you.

Then it would have to be 4-core cables, right? Unfortunately, they are only 3-core. Can I run or have an additional cable laid separately for the continuous power to the Eltakos? As I said, space is not a problem, and we have specially installed empty conduits up to the attic. So that would not be a problem; everything is easily accessible.

With an additional cable, it would be easy to disconnect. I still don’t quite understand your setup. Do you have empty conduits up to the spots? Then you just need to pull a 3x1.5 cable there up to the distribution box. Or does the empty conduit only go up to the switch? In principle, it would work then.
You could then use the brown/black wire as the power supply with the push button and use the blue wire as the "output" and connect it to the relay, which is then located in the distribution box. So you have constant power on the phase and switch the blue wire. However, this is much debated and at least not well regarded. Feel free to google "N/blue as switching wire." But this only works if all cables go to the distribution box.

With 5x1.5 (usually you don’t use 4x, but directly 5x. It’s also cheaper than 4x), it would look like this. I have attached a picture. The one in the green box is only to show what it looks like with a cable that has more than 3 cores. You use one as the phase that goes into the push buttons and is bridged in the flush-mounted box. This way, you have constant power at the relay, which is located in your ceiling. The lights are connected accordingly there.
You use another wire as the switching wire. When you press the push buttons, it applies voltage to an input on the relay, which then dims the spots.
The left side is just to show how I currently understand it.

I will try to describe it again. In any case, many thanks for the help. So: In principle, the electrical rough installation is completely finished (plaster and screed are also done). Sockets are installed. Now the electrician wanted to install switches and push-buttons (spots are not installed at all yet). For all of these, 3 x 2.5 was laid. Of course, for each lighting circuit, all the way to the distribution board. We have all rooms on the ground floor. The attic will not be developed. We have visible wooden beams everywhere downstairs, on top of which are drywall and OSB. Above that, again, wooden beams running crosswise. Between the wooden beams comes 20 cm of insulation. And basically, the ceiling spots will be sitting in the insulation. Since it is not insulated yet and everything is open, we have space. As a precaution, we once laid power and 2 empty conduits from the lighting distribution on the ground floor up to the attic. So basically, we have power upstairs. I hope it is somewhat clearer now and I hope it is still possible.