I found this program: https://github.com/cirala/vifmimg for previewing pdf files, image files, video files, etc., but I was wondering it it was possible to do the same with office files, e.g. .docx, .doc, and .odt for "word"-type files, .xlsx, .xls and .csv for "excel"-type files, and .pptx, .ppt, etc. for "powerpoint"-type files?
I only know about catdoc for *.doc and docx2txt for *.docx. Both translate things to text.
Maybe something like LibreOffice can render first page of a document into image, then it could be integrated into vifmimg, but I haven't seen anything like that (didn't really look for it either).
I figured out that I can use pandoc for .csv, .odt, .docx, and .rtf.
I can also use catdoc for .doc as you suggested.
Finally, I can use xlsx2csv and xls2csv, then pipe into pandoc for .xlsx or .xls respectively.
Still looking for a way to preview .pptx files, but probably none will be found.
I figured out that I can use unoconv to convert .pptx to .pdf, then preview that using vifmimg.