China Southern has SFO to Sydney at $589 round trip for many dates in April and May 2020. Unfortunately the flight tends to require an overnight in Guangzhou when transiting CAN airport. That may lead to some major issues getting back into the USA without a quarantine based on current restrictions.
Anyway, my primary purpose in posting airfare deals during the coronavirus pandemic is to maintain a database of airfare ticket prices to places around the world and not necessarily to encourage travel during this period. Last week I came across a $550 ticket price for SFO to Barcelona as an around the world itinerary to Barcelona via Singapore on Singapore Airlines outbound and Tap Portugal via Lisbon to SFO on the inbound flights.
China Southern Airlines San Francisco SFO – Guangzhou CAN (overnight) – Sydney SYD – CAN – SFO