Hi there, @PurelyLocal !
The 5G Internet service is only available in selected areas on the Optus 5G Network with the modem supplied by Optus. There may be technical or other reasons that affect your ability to access the service at your address. The service qualification check and map is an indication that you are within 5G coverage, however it does not guarantee that your address is 5G serviceable.
The 5G rollout is an ongoing process though and we suggest keeping an eye on our Optus 5G page for updates and changes.
@PurelyLocalYou got the standard non answer from Optus for your question.
To get a heads up on if Optus have installed 5G on a tower near you, which indicates that Optus are in then process of rolling 5G out near you head on over to the following site and enter your address and look at the tower info to see if any have Optus 5G on them. Be aware that this does NOT mean that Optus will enable it quickly as the tower near me that I can see from a bedroom window has 5G installed in August, but it is still not showing as being available in the Optus map.
And if you ask Optus when 5G will be enabled for the tower that has 5G on it you will get the same non answer instead of "I do not know and the systems I have access to do not show the info, so keep an eye on the 5G maps", which is IMHO a valid response.
If you think this answers your question please mark it as being answered.