Land Planning Software Recommendations for Houses

It doesn't make sense for laypeople to just move walls. Structural integrity, wastewater, etc.

Well, you could define load-bearing walls as non-movable in the software. And an intelligent software could, for example, report the wastewater problem as an error. Or provide optimization suggestions, basically code like "If the distance between toilet/sink and the wastewater pipe is greater than X, then report: 'Warning, toilet piping will be expensive'" or something like that. If we can manage something as complex as autonomous driving through software today, then intelligent planning software is no rocket science. But such software would be expensive. However, the construction industry has been getting tons of money in recent years. Purchase once and enable customer access via a user system.

Actually, you should have enough spatial imagination and manage without 3D.

That is, of course, a helpful hint. No questions left unanswered :)

In the professional sector, starting at 1000€ per license

That's intense. Isn't there any cheaper software that would meet my criteria above?
Which software do forum members here use? That was my original question.

We were able to test our (quite special) house color directly with the general contractor in the program for approval, for example.

Program on your laptop/PC/in the cloud or were you only allowed to look at the screen with the GC consultant?

We had screensharing sessions. However, I have to correct myself regarding the price, ArchiCAD does not cost 1000€ but 2000-4000$ depending on the edition :/

I used Sweethome 3d. But it can hardly do anything of what you want. However, it is enough for a layman to get a basic idea.

Professional software can do a lot but on the one hand it is expensive (although there are sometimes free trial versions). For laymen, however, the learning curve is much too steep. You first need 50-100 hours to familiarize yourself in order to achieve what you want, and then maybe 100 hours to work on your actual floor plan. And then it is basically just a sketch that a professional still has to work on.
So it’s really not worth it.
From a company’s point of view, it’s not worthwhile at all. It doesn’t save time.
With a room program and a list of requirements to the architect and then three to four planning rounds with them. That is maximally efficient.

Which software do forum members use here?

The software is usually called Architect. ;)

Program on your laptop/PC/in the cloud or were you only allowed to look at the screen with the general contractor's consultant?

Screensharing. As others have already written: This is all professional software that you would have to work your way into yourself. The effort is disproportionate to the benefit.