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.
Well, Gimp is great, but still lacks some features for the professional user, eg a good RAW support, it can substitute PS if you also use Krita to fill the holes Gimp still has-