Well, from what I'm seeing Apple Pay is gaining traction here in the U.S. Since the NFC part isn't proprietary, it works with almost any terminal (Ingenico, Verifone) that supports contactless payments (with few exceptions).

It supports Apple Cash, which in turn can funded via a bank debit card. (kind of like Venmo). There's no transaction fee with Apple Cash.

I believe there are currently no additional fees on the merchant side to accept Apple Pay [1], unless the customer uses a credit card via Apple Pay in which case the standard credit card fees apply.

[1] https://support.apple.com/en-us/HT204274