OK, I ended up with the following ten categories:
Part of me thinks that Help and Tips could be combined, and that Feature requests (and maybe even Bug reports) could be folded into Feedback. But I will leave it like this for a little bit and see what y’all think.
By the way, the difference between Announcements and Backstage is that the former will be used for announcing big new releases and other news, while the latter will be for sharing the process and progress of feature development as it goes along.