The hot mess of Federal, State, and Local Governments in Australia

What level of government is responsible for what? And if they have overlapping responsibilities (and they do) then what?
Can an emergency simply override everything we know to be lawful, so we are led by a "National Cabinet" that just makes decisions on the fly, and of which the noted meetings would not be made public?
If anything, the COVID-19 scam has proven that that is all possible.