!australia@aussie.zone is the more general Australia community, but not a big deal given it's early days and things are still working themselves out.
Not sure how to turn the above into a generic clickable link (that will work on any instance), but you should be able to search it.
You can use third party sites to find communities, if you're not seeing them in the search (because they haven't federated yet) with one of these:
https://lemmyverse.net/ https://browse.feddit.de/
But that's still going to a third party site so it would nice to have it integrated into the interface.