Is there a viewer for Writer?

Like the MS Word viewer for user only view the doc\docx file and don’t want to let them save and edit the file. Since MS word viewer not support viewing the embedded file in Sharepoint

As captioned . Thanks
Not support viewing the doc\docx file embedded in SharePoint with IE11 in Windows 10

The viewers for MS products exist for copyrighter reasons, so that users that have not yet bought MS products be able to see these documents. Since LO is free for anyone to download and install there is no reason (at least for the moment) to create such viewers. For prohibiting of edit other means are used.

There’s not a standalone viewer application, but you could select all the content and protect it (prevent it from being edited) with a password, as described here: Protecting Content in LibreOffice Writer - LibreOffice Help

The .pdf format (Portable Document Format) is designed to provide the formatted document just to be viewed. In LibO you can select this format as File > Export as > Export as PDF. This allows someone to view but not change a document. Document formats such as .odt / .doc /.docx etc. are revisable and not intended for read only display, and can look different on different systems depending on the individual setups.

Most users already have a .pdf viewer installed. This is smaller and faster than using a full office system to view the original source document. In addition, you keep the original source and can protect it from anyone having access to it. Although it is possible to modify the .pdf on some systems, this only gives access to a formatted copy, not the original .odt file, with its inherent usage statistics.

True, but there’s a change coming. More and more people want to edit PDF files and LibreOffice already allows limited editing. Give it some time, then all PDFs will be as editable as any file in MSO or ODF format.

If an organization needs to make sure someone views some documents without possibility to edit them on a SharePoint instance, that should be done using SharePoint policies (assigning proper access rights, etc), not by installing read-only apps.

If somebody can access your document, they can probably move it to a medium where they can open it for editing.