Graphene OS has NFC enabled and you can turn on sandboxed google play services. Have you tried following the steps that people who use a normal android pixel do? If you haven't found where the error is when following the steps everyone else does, finding out if there is even a problem will be difficult.
Also, just on a side note, for financial security and privacy purposes, I wouldn't trust your money with a company that tried to sneak in a "2500 USD for misinformation," clause in their TOS before removing it due to backlash, nor would I recommend using paypal/credit cards since the credit companies and other 3rd party sell all of your purchasing habits and whatnot. If you care about any of that stuff, I would suggest you use cash or monero instead. Again, just a suggestion. Let me know which step you follow where the NFC doesn't work, and I will see if I can help.