As you noted, Indonesia is not yet included on the list of countries and areas that accept Apple Pay.
Apple Pay is a contactless payment mechanism that allows you to make safe payments with Apple Cash and any debit or credit card you connect to Apple Wallet. It also allows you to send and receive money using Apple Pay payment cards.
Apple Pay allows you to make secure payments using iOS, iPadOS, and watchOS apps, as well as websites using the Safari browser.
Apple Pay may be used to make payments at retailers in the United States that show the Apple Pay or contactless payment icons. You may also send money with Apple Pay using the Messages app on an Apple device. Your Apple Cash card is the default payment method, but you may change it.
When you make a purchase at a store, Apple Pay generates a device-specific number and a one-of-a-kind transaction code. Apple does not store your credit card information on your device or on Apple servers. Furthermore, card numbers are not shared with retailers.
To send and receive money using Apple Pay, you must be at least 18 years old and a legal resident of the United States. If you are under the age of 18 in the United States, your family can set up Apple Cash on your behalf as part of Apple Cash Family. Apple Cash Family accounts have the ability to send and receive up to $2,000 each transaction or within a seven-day period.