Simple Smart Home System - HomeKit: Bosch, Opus or others?

In general, I am of course in favor of KNX, but that probably won’t work with the requirements and the budget. Opus works perfectly. Multimedia then only works with HomeKit or through integration with Control4. The "central unit" is not really one; it is "only" a HomeKit or LAN gateway. The system itself also runs without a central unit. You would have to create the automations in HomeKit or Control4, although Control4 is not a do-it-yourself system. Generally, the question arises whether you want (!) to do everything yourself or if you need to rely on professional help, which again costs money.

/Edit: I just noticed that Opus now also has a Mediola connection. That could allow for quite a few things.

untergasse43, many thanks for your input! I hadn’t known Control4 and Mediola before and had to spend two hours getting familiar with them.
In any case, I will have to read up on this more thoroughly.
If I understood correctly, both options are extremely flexible solutions.
As far as I gathered, both offer software (Control4 OS3 and Mediola AIO Creator NEO) with which I can easily create individual automations and buttons. Additionally, there are gateways to be purchased that provide interfaces to different manufacturers.

I liked Mediola a bit better here. The only downside would be the plugins. For example, Opus costs €149. This would be acceptable as a one-time investment, but apparently, one only gets updates for 12 months, so this can presumably be considered an annual cost. What I have not yet grasped is whether the Mediola AIO Gateway replaces all other gateways like, for example, the one from Opus greenNet, or whether it communicates with the gateways.

Just a basic question: Are you free to choose the Elis or are you bound? If you are bound, what experience does he have?

Elis are presumably electrical installers?
We will very likely work with a local contractor and therefore be somewhat more flexible than with a system integrator. Accordingly, I would let the installer know the desired system in advance. ;) If someone puts up resistance here, then another service provider must be found or the trade taken out and assigned on our own.

We have Somfy installed. With that, I can manage the "must". Some "could" (garage door, smoke detector) are also possible. I am not sure about the "should" ...

Are you dependent on the tahoma box or do you possibly have Somfy integration for Home Assistant in use?

Are you dependent on the Tahoma Box or do you perhaps have Somfy integration for Home Assistant in use?

At the moment, I only use the Tahoma Box for roller shutters. This way, they can also be controlled via the app. Lighting is possibly also planned.

The Somfy API seems to have been available since 2018. Has anyone already been able to gain experience with it?

Maybe a bit of a "makeshift solution," but I really like using the Shelly for sockets, garage doors, blinds, dimmers and I am very satisfied with it. The connection is made via HomeBridge into HomeKit. If you have a HomePod or iPad, that can be the control center and you can create automations directly via iPhone/iPad and also control it remotely. Of course, everything can also be done by voice (Siri, open the garage :P)