Laying network cable

So I am not a builder, I am renovating my house to live in it, not to sell it. Do you always buy your car with the equipment that will sell better in the end? That would be somewhat reasonable since you probably change your car more often than your house.

We don't need it at the moment and don't want to pay the costs for it either.

That is your personal opinion, but it doesn't help with my question.

What is unclear to you?

Simply place CAT at the supposedly necessary points and that's it. You can leave out repeaters; they are really as necessary in new buildings as a goiter. Just provide access points for WLAN on each floor (if one per floor is not sufficient).

Telecom connection - router/modem - switch - patch panel - LAN cables (Cat7) - outlets This is the order from the house connection. Either you use VOIP phone or you should run a telephone line from the router to the granny flat. Otherwise, you need DECT repeaters and that is not a good solution.

Well, that's quite a statement already. So I'll lay down a LAN and telephone cable in the granny flat, then we won't need a new phone and can continue using everything as before.

Switch and patch panel are two components?

How have you solved it at the distribution point so that it looks good? A few LAN cables will come there, they can't just be sticking out of the wall, are there nice solutions for that?

What is unclear to you? Just lay CAT cables where you think they are needed and that's it. You can forget about repeaters, they are really as unnecessary in new constructions as a goiter. Just provide access points for Wi-Fi on each floor (if one isn't enough).

It's clear that anyone can install empty conduits and pull cables, but my problem is what happens next. You can't just plug everything into the FritzBox; you need this distributor for that... And then I just don't know exactly how to set everything up nicely in terms of appearance... Is the patch something like a distributor? I plug one cable from the router in and then have, for example, 10 outputs that are the same?

No
You place all the cables onto the patch panel. Then you connect the ports of the patch panel to the switch with patch cables. The Fritzbox is also plugged into the patch panel.
You do all of this in a small network cabinet.