Creating, updating sidebar, managing bans, managing mods are site exclusive functionalities not possible in any app afaik. Not sure if that’s because the APi doesn’t support it yet or another reason, but you have to do it on the site.

I would be very surprised if it was possible creating communities with Voyager, Blorp, and co. You need to do that so seldom that you can just as well go to the instance's own UI and create the community there.

It would seem like a waste of effort to implement something like that in an external app.