No error. They just won't let me put my card into a n NFC wallet that isn't Evil Pay, and you can't pay using NFC from the app either.
The one that works provides its own NFC wallet, so I don't need to use Evil Pay.
Discussion
To be clear, it's just a small inconvenience. I can just tap my card instead of my phone.
And the reality is that I'm thinking about setting up a two-device system with the SIM-less GOS device tethered to a lock-down mode iPhone. So I can simply use the iPhone of required, really.
I still have an iphone as well, problem is I use it so less frequently it keeps turning off, and then there those times where I need it for something and I have to charge it and wait for it to turn on 😅
I carried an iPhone and an Android device for years and it was a pain in the ass, so I finally picked one and have been doing that for the past two or three years. But now with GrapheneOS working so well, I'm going to go back to a healthy separation of Church and State mode if you know what I mean. It really is worth it.