The Austrian military didn’t just adopt LibreOffice; they actually contributed back to it. Over five person-years of development work went into adding features they needed. Those improvements are now available to everyone using LibreOffice, which is pretty cool.
I wasn’t a big fan of GNU initiatives, and even less of ‘viral licenses’, until I encountered Public Money, Public Code. The more you think about it, the more fucked up it appears to you that governments pay for Windows/365/AWS licenses, using your tax money, because decision makers haven’t got the slightest clue about FLOSS, and if they do, they mostly don’t have the nutsack to implement the sweeping changes that would be necessary to migrate.