Thai airways is only releasing business class within three months of departure to/from AU.
Singapore Airlines you can’t use premium aircraft for business or first, but regional are fine. So for SQ look out of DRW, CNS or PER. That’s going to put a stop in. Connections are on VA.
BR is flying out of BNE to TPE.
Another connecting point is DPS, with VA flying there from MEL/SYD/BNE/OOL, and connections available from other ports, but that might up the mileage band.
Availability is usually pretty good, but subject to the limited number of star alliance partners and schedules out of AU at the moment.
While
Etihad was pretty easy to get, that’s dried up out of australia, but still available out of Singapore easily. I have an upcoming redemption SYD-DPS (five day stop) on VA, then DPS-SIN-LHR on SQ and EY. Gulf Air is also available.