Unfortunately you are not alone in this, many Hong Kongers have huge numbers of miles from credit cards. If you are keen to use them, once you are in Australia you will find some domestic availability, even over Christmas. It may not be the best value you've ever seen, but a few domestic flights definitely did have availability when I was glancing to go between MEL/OOL/BNE/SYD in December. Alternatively if you were to book for European or US flights you will also find seats, its just Asia that, still not living with COVID, has relatively fewer flights available which reduces the chance of redemptions. As long as your miles aren't expiring you can just hope for the best in the future.

Personally I got very lucky and managed to get some flights from UK - Maldives for my family, and joined them there, which reduced my miles from some 700k to less than 150k. Really not the best value flights, but better than a personal exposure to Cathay. I now use and store in the Amex Explorer so the miles can be converted into multiple schemes.

PS: Glad you think the Miles + Cash are terrible value, I agree... but someone at work was saying what a great deal they were as they'd reduced his economy flight from HKD13k to 7k.... I dread to think how many miles were wasted!