Sparked by GhalibKabir’s interesting comment of December 2, 2020 is my comment below.
Yes Russia is very unlikely to accept Indian export of BrahMos to Australia.
In any case Australia politically would reject joint Russian-Indian missile BrahMos because it is part Russian. Australia would be relying on the US to work out countermeasures Against BrahMos.
On an electronic intel level BrahMos might be packaged with hidden extra Russian spyware software. That may also render it inoperable in attempted use against target ships carrying Russian friend-or-foe transmitters.
Past Russian nuclear and missile assistance to India's Nirbhay, nuclear capable cruise missile, would also turn off Australia.
There may be more interest likely in Israel's small "Baby Boomer" SSB platform supersonic endrun Popeye Turbo n-SLCM.
More overtly (and in joint Australia-US character) is:
https://edition.cnn.com/2020/12/01/australia/hypersonic-missile-australia-us-intl-hnk/index.html of Dec 1, 2020 "Australia partners with US to develop hypersonic missiles"
"(CNN) Australia will jointly develop hypersonic cruise missiles with the United States in a bid to counter China and Russia which are developing similar weapons, Defence Minister Linda Reynolds said on Tuesday.
"We will continue to invest in advanced capabilities to give the Australian Defence Force more options to deter aggression against Australia's interests," Reynolds said in a statement.
She did not reveal the cost of developing the missiles or when they would be operational.
Australia had set aside up to 9.3 billion Australian dollars ($6.8 billion) this year for high-speed, long-range missile defense systems, including hypersonic research..."
Likely synonymous with the US developing a larger longer range SM-6 - with SM-6 already ordered by Australia, Australia may be part funding the enlarged version. Further reading https://en.wikipedia.org/wiki/RIM-174_Standard_ERAM basically in the BrahMos class.
Also see https://www.aspistrategist.org.au/australia-is-getting-the-long-range-missiles-needed-for-a-contested-indo-pacific/“This is likely to be the SM6 [ https://www.thedrive.com/the-war-zone/27068/navy-to-supersize-its-ultra-versatile-sm-6-missile-for-even-longer-range-and-higher-speed ] missile”
An authenticly hypersonic US missile, that might be passed on to Australia by the 2030s, is the under development "Conventional Prompt Strike (CPS)" missile.
I haven't read much about Vietnam building an n-deterrent (with Russian help?) but it would make sense against China. However Vietnam might reason that it would need a too large, hence unaffordable deterrent, to give China pause. I see Vietnam has curtailed its nuclear energy plans.
Philippines is still under US Treaty/control [see Diplomat paysite] stopping Phils doing its own n-deterrent.
I class Phils with Cambodia, Laos, Thailand, Malaysia and Myanmar as being (understandably) too frozen in fear in Chinese headlights to contemplate a n-deterrent. It cannot be easy for the mainland Southeast Asian countries, knowing they are but a short Chinese tank drive away.
Indonesia already has the money to go nuclear, but that would form the major headache for Australia - enough for Australia to also go down the n road.