This is certainly a growing trend which was first started amongst end-users themselves, and slowly we've seen a few news media outlets also following suite. So far, only a very few government agencies have actually followed. Coming to mind are also The Netherlands. What is attractive for many organisations and agencies on Mastodon, is that...
Seven: https://social.bund.de/@HBBuergerschaft and also the federal parliament: https://social.bund.de/@hib_Nachrichten
In the case of the SH instance the government seems to be the only user, while on social.bund.de you’ll find a flurry of different stuff, both state and federal level, say the federal weather service, unsurprisingly quite popular. I’m actually quite surprised Bavaria of all states is using the federal instance.
Instance choice is going to be complicated with some SH institutions because on the one hand we’re just as much as a “state’s rights and sovereignty” state as Bavaria (pretty much the only thing we have in common short of agriculture), but OTOH share quite a few with Hamburg, say, statistics.
These things are never as easy as “just open an account” when it comes to states.