Nope. Only on the grey market. To be fair, most grey market sellers if it do have a fairly robust refund set up cos Australian law dictates they must. But some of them will make you feel like you're trying to get blood from a stone if something goes wrong...
You buy what you hope is a genuine Steam Deck from someone who has brought it here from the USA for 🇦🇺$1,000.
Valve won't help you if you have problems, because you are in Australia. Depending on who you bought it from Australian consumer protection laws might not apply.