I saved my SG bank credit card & Revolut card in my iPhone. Tap my iPhone before to purchase RM1 Vanilla Coke at a vending machine here. It charges S$0.33 to my statement. Done it before at petrol station also

Conclusion:
Apple Pay is just a mode of payment. It can be use anywhere that accept tap and wave payment terminal even in Malaysia. Only Malaysia bank cards don't allow Apple Pay mode yet. Perhaps high fee is involved?