Construction costs are currently skyrocketing

But the future would be that even a TV and actually all devices (at least those that do not need to heat and therefore have a high power consumption) have a small battery and are constantly fully charged.

Oh dear, what an electrosmog if you want to charge all that wirelessly. I might as well put my head in the microwave :D And then there’s the low energy efficiency, you need double the power, so double the costs, instead of with a cable. Or even worse, the more distance you have to cover. That will never happen.

Please tell me how your overall WLAN concept looks.

Pretty central a strong router - done. That’s how I have it now too and, as I said, never had a problem with it, even with 4 kids simultaneously in Teams / Zoom, me working from home and my wife surfing and streaming.

Timber frame construction or solid wood? With solid wood, it will bring little joy.

Wooden frame construction or solid? With solid, it will bring little joy.

One should differentiate solid. For me, Ytong is not solid. Solid is reinforced concrete and KS stone.

Exciting. We currently live in an apartment in a multi-family house and Wi-Fi was simply never great, even after we got an additional access point (although we probably shouldn't have skimped there, but it already felt excessive to need one at all). And over the past two years, we've increasingly switched back to cable because it was just more stable and otherwise annoyed us too often. Maybe the neighbors are just interfering with our signal too much ;) but LAN ports in all living rooms are pretty high up on our wishlist for our own place.

Pretty centrally a strong router - done.

That's how I have it now too and as I said, never had a problem with it, even with 4 children simultaneously on Teams / Zoom, me working from home and my wife surfing and streaming

Of course it works, but in new buildings it hardly costs more to do it better...
My TV, for example, sometimes pauses for a moment when it's only connected via Wi-Fi. Sometimes it also doesn't connect properly and needs to be restarted. Nothing serious, but to save a few euros for a cable?