Uh, I know n=1, but I used to work in a public research lab in France for almost a couple years, and already back then (4-5 years ago) they used tons of FOSS. Zimbra, Mattermost, Gitlab, the works. So I don't think it's all just theater.

Then again, if your employees still need PowerPoint, I say let them have it for now. You cannot switch a single company to FOSS overnight, let alone the entire public sector of an industrial nation.