Electrical installation - Retrofit switches/buttons wirelessly

There is no clear answer to this question. But you need all 3 wires at the light switch and light outlet to be as flexible as possible. Simply put, you should also be able to install a socket at that point, then almost all options are open to you. Just as T_im Norden has already described.

Star wiring, basically.

Here is an example of a light switch. A brown cable (phase) goes into the switch and out again. The neutral conductor (blue) is not connected there at all but is clamped in a WAGO terminal (right in the picture).

Here is the wiring diagram of my actuator FL62-230V:

How do I best proceed here?

You have everything you need on this light switch. Simply follow the connection example and connect the actuator.

okay. Now it is like this: my electrician installed switches supposedly to hand over the house as "operational." With push buttons, "you would have to keep pressing for the light to stay on." Since I wanted to install the radio actuators myself, the electrician planned the switches. After handover, I would have to replace the switches with push buttons + radio actuators...
I'm really annoyed. Even though I constantly mentioned that we would use radio actuators, and even wanted to obtain them through the electrician - he said "you can do that yourself later"... I think now I know why...

Still, just for my understanding:
The radio actuator takes over the function of the conventional light switch - so the conventional light switch is only responsible for sending the PRESSED signal to the actuator?
What happens if my logic control is deactivated? How can a light switch as a push button still turn the lamp on/off? Does the radio actuator then take over as well (just directly instead of via radio)?

Yes, then the signal goes through directly, hence the wiring by the electrician. Look up Shelly 1 - installation / integration in a two-way switch.

Now it is so that my electrician installed switches supposedly to "hand over the house in a functional state". With push-buttons, "you would have to keep pressing constantly so that the light stays on."

Yes, and that is a good thing. Because you ordered a functional product and you are getting it as well. Just because you don’t order winter tires and want to put them on yourself, the car dealer will also not deliver the car on bare rims in December. No, summer tires will be included.

Since I wanted to install the radio actuators myself, the electrician therefore planned switches. After handover, I would have to replace the switches with push-buttons + radio actuators...

Yes, which in itself should not be a problem, because as we have already established from your pictures and statements, everything is prepared so far for the conversion.

I am really annoyed. Even though I constantly mentioned that we would use radio actuators, and even wanted to get them through the electrician – but he said, "You can do that yourself later"... I think now I know why...

He has his contractual terms and he must adhere to them.

The radio actuator takes over the function of the conventional light switch – the conventional light switch is then only responsible for passing the PRESS impulse on to the actuator?

Yes, that is basically how it works.

What happens if my logic control is deactivated? How can a light switch still switch the lamp on/off as a push-button? Does the radio actuator also take over that (only directly instead of via radio)?

Don’t get so hung up on the light switches. In a functioning, more or less automated installation, they are truly the last fiddle. The actuator takes over everything, the entire control (relating to this one lighting group).

Then it only reacts to the impulses from outside. These can come from push-buttons, switches, sensors, logic, phone, etc. The actuator processes these impulses and performs the appropriate actions.

I looked at your first post again. Your wiring is conventional according to your description and not star. Therefore, a push button can only work if there is an actuator inside, otherwise you need a switch. What does the order say for the electrician, push button or switch?