Yes, LibreOffice can import and export Excel/Word files. If you're trying to do full layup with them (I am a layout snob, that's a job for InDesign), you'll probably have a hard time. And there may be some functions in Excel that are only in Excel. So it depends how much you're leaning on specific complex features.
There are also the online Google versions. Again, it depends on what you use the programs for and how.
For me, Word docs are about text with minor formatting, so I could probably use WordStar on DOS :) I do push things a little further with spreadsheets but usually I'm presenting the results and not the intermediate steps. Your use case may vary.
