I can seem to get it to work, it always gives a message "this phone can't be used to pay in stores. This is may because its rooted or altered in any other way" Is their any work around ?
GPay doesn't work with GrapheneOS as it doesn't pass the SafetyNet's ctsProfileMatch check. You can read more about it here..
Some more reference threads:
To French GrapheneOS users: if your bank supports Paylib, you can use it to make contactless payments. It works perfectly fine on GrapheneOS. :)