Software 3D visualization experiences

But I found it very helpful for understanding 2D floor plans

Do you mean in the sense of "planning in 3D and then 'jumping back' into the floor plan perspective to recognize the space within it?

I see the problem with people who basically 'have no knack for it' is making big leaps: by the time the object becomes "experiencable" in 3D, it is already colorful and furnished, i.e. one jumps from the "blank sheet" to a high level of detail. In other words: the layperson sprints straight into the detailed scale. The professional planner, on the other hand, starts every project at the preliminary design scale and level of detail, no matter how long their experience is.

With technical drawings, finished floor plans are no different, I wouldn’t even bother with them for my wife, for example.

I prefer floor plans in architecture books at a scale of "approximately 1:328" – except for the sanitary fixtures, which are "naked."

And: I either have an idea or patience. Actually, scribbling is already too slow, but if I had to push a mouse to note a spatial thought, that would be almost torture.

I like to use Sweethome. It is a bit of work to create the floor plan and furnish it. You should not use the given dimensions. However, after editing, the furniture has the size you have/need. We have used the program many times and it has served us well for furnishing.

With Sweethome, everything I created looks creepy. No chance of depicting our house in a way that gives a 3D impression of our home. Not even the shape of our living space can be represented. Not to mention the available furnishings. Stairs, stove, shelf, windows, surfaces... don’t even resemble our design. How is it possible to plan so restricted, without overlooking good solutions and being creatively limited?

Maybe it also depends on the type. I have a good spatial imagination, so that kind of visualization is enough for me. You can still download furniture afterwards. I also often just put boxes down when I want to know how much space is left or how it looks when something is there.

It might also depend on the type. I have a good spatial imagination, so this kind of visualization is enough for me

That is the problem of the OP, he is looking for a solution for people with less spatial imagination.

For me, SweetHome3D used to be the least bad option. By now, I am even very satisfied with it. How one can use such software on a tablet is a mystery to me. I would go crazy.