I have done some quick search, but so far it seems that org mode does not really support exporting written text in a horizontal (that is landscape) direction

Would a feature like this be possible in the future? For example:

#+BEGIN_VERTICAL

Some text written in a typical horizontal/portrait fashion, but is rendered vertically upon export when inside these tags.

#+END_VERTICAL

Or maybe it should be called #+BEGIN_LANDSCAPE / #+END_LANDSCAPE, I am not sure :).

Thanks for all your time and help,

Marek