Everything should be on their website, plus posted to the top social media (by popularity) to make it easier for people who want a push feed.

They should also post to at least one social media site that allows full reading for free without an account and supports notifications (possibly only with an account along as that is free), unless one of the top sites they post to satisfies this.

The reason for this last is so that if there is demand on some less popular medium for these posts, someone interested could build something to subscribe to the feed on the free site and repost it unofficially to the other service.

It's called "The Web" and every government org pretty much already has a website. All they have to do is publish something on it.

I mean, I think a small website/blog with an RSS feed would be fine. If they really want it in social media format they could host an at proto PDS.