You've posted this twice?
Pie 9.x was only released 5 months ago, I think Optus has to test it before releasing it.
There are other consumers on the forum complaining they aren't releasing updates for Huawei Mate20 either. So I'm not sure if things have stalled due to the Christmas/New Year shutdown.
Late Jan to early Feb according to this - https://yescrowd.optus.com.au/t5/Blog/Android-Software-Updates-24-01-2019/ba-p/528750
Just to add to the info above, Google released it some 5 months ago but then Samsung need to modify it themselves for their current handsets (S8, S9, S9+, Note 9, etc) + all the variants there are around the world for various countries. It's then supplied to Optus to test and goes back and forth between Optus and Samsung until any network bugs are ironed out and then released to you which is why there's a delay.
Either way, not long now!
It's not far off @Kaz1
I'll have my next device testing report in my inbox by the end of the day.
If there's been any changes to the original timeframe we've quoted, I'll have the blog updated.