From experience, I can assure you LibreOffice is no real equivalent to Office. I can guarantee you that you will have people asking you about stuff that Office does just fine but isn't really possible in LibreOffice or is a major hassle.

I have been the one touting alternatives since I was very young and foolish (in particular advocating for the free Apple suite), but I have run into enough problems I couldn't solve that I don't bother anymore.

Microsoft is winning with Office because everyone else is more incompetent than them; it's simple as that. If someone could come up with a true, cheaper competitor, everybody would switch, regardless of the file format arguments. In fact, the generalized use of Google Suite for the simple stuff shows that it is the case. When people insist on Office, they generally have a good reason, and you should trust them.