Go cashless in Hong Kong
Not all Mastercard / Visa types that are already connected to my Apple Pay are supported by this app (despite they are all from the same bank - for example in the case of Revolut, only premium cards work with Octopus). The currency exchange rates are pretty bad (compared to Revolut or other fintech services). But it allows me as a tourist to pay cashless even in small local places where payment cards are not accepted. It helped me a lot!