Laying LAN in a purchased prefabricated house - timber frame construction

Yes, everything via WiFi or Powerline. In my opinion, networks are totally overrated.

You can do everything via WiFi, but for reasonable WiFi coverage you need access points, and for access points you need a LAN network. Personally, I only use WiFi for what it was originally developed for, only for mobile devices. Everything that stays put is connected via LAN, and this approach also relieves my WiFi.

Powerline should only be used as a very last resort.

You can do everything over WiFi, but for proper WiFi coverage you need access points and for access points you need a LAN network. I personally only use WiFi for what it was originally developed for, only for mobile devices. Everything that is stationary is connected via LAN and this approach also relieves my WiFi. You should only resort to Powerline as an absolute last resort.

Powerline can be tried first, but before you start knocking down walls... And WiFi – in the OP's case it was about wooden studs, not reinforced concrete. You can reach almost every corner with 1-2 decent repeaters. That can also be tried...

Powerline can be tried out first, but before breaking open the walls... And WiFi – in the OP's case it was about wooden studs, not reinforced concrete. With 1-2 decent repeaters, you can reach almost every corner. That can also be tested...

That was also my approach. Repeaters halve the bandwidth. We also don't have ‘dense’ masonry and can manage quite well with WiFi. Even the TVs were once connected exclusively for streaming. We didn’t even have access points for that. However, we use 2.4 GHz in the network, so with a higher range. With the faster 5 GHz, the range is probably noticeably worse. For us, the facade renovation gave the – probably one-time – opportunity to lay cables. If the OP is now renovating inside, in my opinion, that is also the best chance for it. Powerline can certainly be tested. The hardware for testing costs about €130. I ordered and tried it. I was not satisfied. Therefore, the hardware was returned.

Cat.8.1 does use RJ45 connectors. ;)

That is correct.
That is why CAT7 will probably have no future due to the different connectors. It's not just the cable that determines the network.

I only meant

And the GG45 connectors are not compatible with RJ45. Therefore, they probably will definitely not prevail.

... just to point out CAT7 :)

A quick search showed that 100 meters of CAT8 duplex is about twice as expensive as 100 meters of CAT7 duplex.

One more thing :)
I mention this because we are currently also facing the same situation. With us, a patch cable now runs from the FritzBox (router) to a switch. The outputs (cables) from the switch are now distributed over the facade into the respective rooms and end in the network sockets. In the living room, I had connected a TP access point to the socket. The second connection goes to the TV. We then had the problem that streaming partly did not work, even though a connection to the FritzBox via the patch cable was established. I identified the access point as the culprit. It is important here that the router and the access point must have different IP addresses. No idea if this knowledge is obvious. I had to figure it out first... :D

It is important to ensure that the router and access point have different IP addresses. No idea if this knowledge is obvious. I had to figure it out first ...

That is rather absolute basic knowledge and has nothing to do with the actual wiring that this is about.