Actually you don’t need multiple accounts, you only need one in a specific instance and can interact with other instances (My account is registered at programming.dev).

The UX is extremely wonky and I had to look it up, but you can go to the search in the top right of your instance’s main page (not the “communities” subpage) and search for communities and filter by “Communities” in the top left

The sooner a community can be decided on, the better. /r/rust should then link to that instance in their privatization message so users who’re out of the loop are not completely lost.