Just a few tips. Most "government" postal services like USPS, AusPOST etc (including EMS) are using passenger aircrafts for shipping. Because passenger fleets are grounded it's very difficult to deliver anything with "default" shipping provider. Courier services like DHL, FedEx and UPS are using their own aircrafts to major destinations and therefore could deliver. So if you want to purchase anything from overseas then try using UPS/FedEx/DHL. But please do check their websites if they are delivering to Australia from the country of origin.
UPS:
https://www.ups.com/cn/en/service-alerts.page?id=alert1 (delivery from US, Europe etc to Australia is possible)
DHL:
https://www.simplydhl.com/covid-19updates (US to AU - possible, Europe to AU - technically possible as webb, but check with the shop)
FedEx:
https://www.fedex.com/content/dam/fe...cts_Apr_23.pdf (Not clear, better to drop them an email to clarify)