Gambling is legal across Australia, including both physical gaming environments (like casinos and betting shops) and gambling online. This has always been the case, and will remain the case indefinitely.
While players are free to choose how they gamble and the sites they use, there is legislation on the statute books that deals specifically with gambling operators. The effect for players is minimal, besides notionally constraining the types of gambling products they have access to. All of the legal burden is on the shoulders of website operators located in each state or territory, and even still, many international operators choose not to comply.
That means you’re free to gamble in any way you choose nationwide, with absolutely no worries about running foul of the law.