Smart home without switches? P.Hue, Home Assistant, Homematic wired IP

@ Thank you very much, that helps.....
What is still important to me is remote access. I want to see how much electricity is being consumed, whether someone is present.
And if no one is there, turn off the light, or heat the room before someone arrives, etc.

Therefore, I need to make the whole system controllable and linkable from outside, how does free@home behave in that regard.....?

The best way to do this is via a VPN connection. These are basics. Please do yourself a favor and get someone on board who knows about this.

Dear Rick, I will certainly consider that in due course, but right now it is about estimating what is possible and what kind of help is needed, so first you have to understand the system to estimate the effort. I would be very grateful if you could respond not in a reproachful but in a solution-oriented manner...... the VPN connection is only useful to me if I want to actively access the system myself..... but if I want to have it managed smartly now..... so a customer makes a booking and books access for April 28th from 2 pm, I want the front door to know that and the heating as well..... through the information from the website without my intervention.....

What does the solution look like? I would find it great if that could be done via Bush Jäger!

Free@home can be controlled from outside at any time without extra costs. It works very simply via app

I would need to ask more precisely once.....how would the interface to F@H be there, is the app cloud-based? Does the cloud have an interface? I basically want my booking software or something else to then control the app and thus the apartment.....

Whether it is that simple, I unfortunately do not know. However, since the last update, there has been an API interface. But there will be nothing off the shelf for that; it would have to be programmed individually.