Which router for our new building?

The devices that are "optional" in terms of redecorating are not at the old and the new location at the same time. Therefore, at one of the two locations, their connection socket is unoccupied (and consequently does not occupy a port on the switch, but only on the patch panel). Are you still confused at this point?

Not confused, I think we are talking past each other... It is mathematically clear to me that the number of currently available connections (and thus required ports) is reduced by those that are optionally used. The question was which switch I should best take. So again: I have 20 ports that are (permanently) occupied by devices and need up to 4 PoE-capable ports on top.

[*] 24-port PoE switch I understand that a "pure" PoE switch has increased (base) power consumption [*] 2 separate switches (=is that the plural?) smaller PoE switch and larger non-PoE uplink bottleneck between the switches [*] Switch that can do both

20 ports permanently in use is really a lot for a single-family house. Is that really the case or is there already a lot of buffer planned? What kind of router is in front of it?

Now I wanted to find out for myself and went to the construction site today to count: there are 23 in total. Of these, 4x buffers in the children's rooms and 1x in the garage, which I had installed (who knows what the Wallbox will need to be capable of later?). I would consider these 5 optional. The rest, yes, are mostly in use. And even if it's "just" for the kitchen machine. All 4 ports on the TV wall are occupied; here I would have preferred to have planned some extra buffer ports. The plan was to have everything on LAN or at least 1 connection in every room (in the guest room we have only 1). I must also add that we both need home office workplaces. Therefore, I don't find it too much. I haven't chosen a router yet. The all-rounder seems to be a Fritzbox. Currently, we are using an Easybox 805, but in the (rental) apartment with the associated cable mess and a lot of (bad) Wi-Fi. If the Easybox is sufficient, then we will take it with us. Seen that way, I can somewhat revise my post from this afternoon and reduce it to about 19 ports + 4x PoE ports.

All four ports on the TV wall are occupied; here I would have preferred to plan some buffer.

I simply use a neat 5-8 port POE switch hanging directly on the double socket. They are not big, don’t cost much (in my case, a Unifi system). I also install double sockets in various places. But why should I install 4, 6 or more sockets? Speed is not an argument either – it’s resolved at the latest at the main switch anyway.

Hmm, it seems to me you are still counting ports when you do that in construction and not the devices that are actually in operation there? And what kind of kitchen machine with a network is that? But well, you can manage with a normal 24-port one, of which at least 4 are PoE.

With 20 simultaneously active devices, the power consumption of the POE switch no longer really matters ;-)
But I think is right. The OP counts connection ports in the rooms that can be occupied, not those of the actually simultaneously connected devices which determine the number of switch ports and not the number of ports on the patch panel which ideally should match the number of ports on the outlets (phew, long sentence ;-)
-> 24 port GBit switch + 8-port POE switch (8-port, because I don’t know a 5-port 19" suitable one)