My 2019 Hyundai i30 shakes at idle, will the dealership be able to help me?

This is not an uncommon thing with some Hyundai models of this vintage. Because of either poor design or materials, some Hyundai engines wear faster than they should. The first signs are rough running, noisy operation and oil consumption. On that basis, I reckon you may have one of those affected engines. That’s supported by the borescope examination that showed wear and the fact that the engine needed two litres of oil to bring it back to a normal level.

It's a fair bet the 1000km monitoring will show the engine has a thirst for oil, at which point it probably needs to be either replaced or rebuilt. My experience suggests that Hyundai is taking this seriously and is replacing engines under warranty with an improved unit that should last much better.

Give the dealership every chance to figure out what’s actually happening under the bonnet and then the time to make it right. You now have what’s called a pre-existing issue, so even if the warranty runs out, Hyundai knows the problem occurred while still within the warranty period. If your case is denied, then it’s time to contact Hyundai Australia’s customer service department and then, if you still don’t have any luck the ACCC which administers Australian Consumer Law and will be well versed with this issue.