Electrical installation in shell construction

Does the router cover the entire apartment with Wi-Fi

Probably not 100%. But I would have used a FritzBox repeater by now.

But I would have used a FritzBox repeater now.

However, the repeater significantly reduces the bandwidth, so I would definitely avoid it in a new building. As for the LAN in the kitchen: I had initially considered it too. Then I looked at the devices and found out that all "smart" appliances in the kitchen operate via WiFi. So you can save the sockets.

The repeater significantly reduces the bandwidth, so I would definitely avoid it in new buildings.

The Fritz repeaters, as well as others, have 2 modes. WLAN bridge or LAN bridge.

In the second case, you extend the range without reducing the bandwidth. Of course, a LAN cable must be connected from the bridge to the Fritz box.

In the 2nd case, the range is extended without the bandwidth reduction. Of course, a LAN cable has to be connected to the bridge to the Fritz-Box.

Then I can also connect another access point there since I already have the cable anyway (only that the access point might even work with PoE).

Ah, I didn't know that. I thought you just plug those things into the power outlet.
So I can connect it additionally to a network socket and that's fine?

Just asking stupidly, is an access point something different from a Fritz repeater?

An access point is connected directly to the router via LAN. Comparable to a DECT base station but only for WLAN. A repeater, on the other hand, receives the WLAN signal from the FRITZ!Box and distributes it from the repeater to the surroundings. For me, a repeater is ideal for an existing building or rental apartment. In a new building, I would avoid the repeater!