Show presenter notes in LibreOffice Impress without a second monitor
Solution 1:
Select View / Notes from the menu.
It shows a format with the slide at the top of the page and the notes below it. Not beautiful but OK for practice on a single screen.
Solution 2:
This feature is not yet developed in the Libre Impress. I have already reported the issue. From following link, you can view the feature request to bugzilla. https://bugs.documentfoundation.org/show_bug.cgi?id=122493