That’s a wonderful idea! While I suppose most of the announcements will be of packages, it is both shorter (one word instead of two, which conforms with the other categories) and better (because it includes other related tools, not strictly Typst packages) to name the category ‘Announcements’.
BTW, I visited the NixOS Discourse forum for a different purpose and noticed they have an ‘Announcements’ category, which is defined as follows:
Any nix-related projects are welcome to post announcements here. This generally includes new projects, project releases.