Oh, that makes sense indeed.
So just for the case, if I have clear sky, I can effectively meter incidently the falling light just at the place I'm at and apply this metering considerations fo the actually photographed scene regardless of the distances involved, right ?

Yes that is correct

Now, if a part of the actual distant scene is covered by a shadow, what I can do is create a shadow of at least approximately similar density and incidently meter it to obtain the necessary exposure, right ?

Yes that is correct as well...it makes no difference if the shadow is caused by a cloud or a standing person...the sunlight does not care what is obstructing it. The only departure would be an enclosed deep shadow which is affected by the amount of light reflected into it from surrounding surfaces.

This sounds very useful, especially for seascapes when a large part of the scene
might be a sea surface heavily reflecting"

Yes that is correct. The reflections from a sea scene would be something that would be considered, of course. Sometime specular high lights will print white if they are of small enough size. I have found that once one begins to use this type of metering that one becomes very adept at reading the scene contrast without the meter and when this occurs one's photography becomes much more intuitive and hence expressive.