I am planning to flight from Brisbane to Osaka and wondering if it was possible to layover at Taipei or Manila airport?
Yes for Manila. https://www.pna.gov.ph/articles/1096970:
The Department of Tourism (DOT) has lauded the lifting of the travel ban on outbound passengers, except Filipino tourists, in line with the Luzon-wide enhanced community quarantine.
Layovers at Taipei TPE were possible on 2020-03-12 but I don't know the current situation (because of How can I know ahead of time whether the Taiwanese immigration and airline flying there will accept my passport?.)
Singapore and Taiwan are both blocking anyone from transiting starting March 24.