The title is self-explanatory.
Well, no, the title is not self-explanatory. LibreOffice has the ability to export documents as PDF files (as the given answers explain). Could you explain?
Doesn’t File → Export to PDF work for you? If not you need to provide more details.
PDF will never become an option in Save As dialog, since it is lossy format.
I don’t think “lossy” is an accurate term to use in this situation. PDF is designed to be a fixed format, although as @mariosv indicates it is gradually being extended to get around this limitation.
Not and I don’t think it will be possible in a near future.
But you have the option exporting as PDF to embed in it the LibreOffice file.
Embed OpenDocument file
This setting enables you to export the document as a .pdf file containing two file formats: PDF and ODF. In PDF viewers it behaves like a normal .pdf file and it remains fully editable in LibreOffice.
Apart form mahfiaz’s answer, have you also tried
File → Print → Options [4th tab] → Print to file [checkbox] ?
In case your are using Impress, you can also check in the first tab whether you want to export, e.g. handout, slides etc.