Blind control for new construction (Many units per switch box)

Thank you thank you!

I've gotten a taste for it!

Are there any other advantages to ring installation (e.g., ring basement, ring ground floor, ring upper floor, ring outside) besides slightly less cable consumption and, when tapping off the line (with ring start and end of the ring line ending in the distribution), using the other end of the ring line?
I lay the load lines in a star pattern...

Do I have to lay an additional network cable, or can I use the other two colors in the KNX cable?

...and do I still have to (just to be safe) lay an NYM cable to the switching units (push buttons, etc.)?

Which manufacturer is recommended?

What I’ve already learned today!! Great!

Well, an open ring + tree structure is the simplest option to reach every place with the same cable. (Ceiling outlets excepted)

And just as you yourself describe, the consumption is lower and you have two ends in case something happens to the ring. One end must then always remain open.

Otherwise, there are no further advantages.

Network cable for LAN is, of course, necessary, as it has absolutely nothing to do with KNX. Although you can connect both, they are two completely different things.

The other two conductors are for the additional power supply of the KNX devices or as a backup in case you have to drill into something twice.

You no longer need NYM at the switches.

You can't really give a manufacturer recommendation; just buy what you like and what has the necessary functions. That is also another advantage of the system. You simply combine whatever you want and everything works together.

...and do I still have to (just in case) add an NYM to the switching units (push buttons etc)?

I would see that depending on how the distribution of DAUs and nerds is in your household. Some people (who are otherwise very nice) feel more comfortable if switches are responsible 1:1 for on/off or up/down each only for one group of consumers. Dimming by double click is not everyone's thing. Therefore, if in doubt, I would provide the analog users with the corresponding analog control elements in parallel.

This approach renders the whole thing absurd.

Why go to the trouble, if you provide an analog circuit for everything anyway.

That would only be the case if the DAU uses all the circuits. But usually the DAU only uses the basics (lights) and leaves the gimmicks (gate control, parking heater) to the nerd alone.

Well, apart from the fact that it only unnecessarily drives up the costs, experience shows that the DAUs adapt quite quickly.