Can't believe it... you get hkd3000 to your Octopus. Use that. While you are using it, no money is depleted from your bank account. Or you can transfer the equivalent 3k from one account to another if that's what you need.
Not sure exactly what's available, but the 1/4oz Krugerrand is available in their promotion and is a relatively mainstream bullion coin
https://www.lpm.hk/en/banner22/2022-...est-deals.html