It would be extremely useful if LibreOffice supported hashtags.
Something like the way they are supported in bear: http://www.bear-writer.com
The particular value would be the ability to share hashtags across different types of document.
I see there is one plug-in currently being developed ( GitHub - jdittrich/Office-QDA-TagTree: Libreoffice-Addon for Qualitative Data Analysis ) this only applies to writer, and it looks as if it will not be ready for a while.