Smart home system recommendation for beginners

This is not a system but only a central unit for, for example, Z-Z-Wave... however, you don't hear anything different there than with the Wibutler...

Since there are so many systems, I don't even know which one would be right for me.

If I may recommend the search function, there wouldn't have been a need to dig deep: - still hotly debated.

But that is about wired systems. The OP has already excluded that:

A wired solution will probably not be possible because the conduits are not dimensioned for that.

That is indeed a reason that is rather far-fetched due to a lack of knowledge, but let's wait and see what the OP says about what has already been suggested.

With a wired system I don't know if the empty conduits are thick enough.

That is indeed a reason which is rather pulled by the hair due to lack of knowledge,

... and most importantly is

I will start the shell construction of my semi-detached house in about two months.

... the right keyword that now is a good time to prevent that. For the project

I want to make my house a bit smarter regarding control and monitoring.

it is wise to run plenty of nerve cords through the house.

Yes, of course, I completely agree with you... so let's wait and see.

Does anyone actually have experience with roller shutter control and Alexa?