We set this up by default on RefflePay.
Android and Apple Devices have specific criteria to hit before they allow payment providers to display the Google and Apple Pay buttons.
Android devices specifically require:
A device using Google Pay Wallet
An OS that is verified by Google to use the wallet.
Using an updated device, i.e.: Samsung 21+
Apple devices in turn have there own criteria:
On the latest version of iOS.
Have Apple Pay enabled as there primary wallet.
Using an updated device.
Apple Pay only works on Safari Browser.
If there isn't an Apple or Google Pay payment option, it is due to customer systems deeming their device as incompatible for the payment.
When a customer goes to pay, they will see the options of card, and PayPal (if PayPal is enabled), in the card options they will see Apple or Google Pay.