this is precisely what I'm interested in!
I found myself at the grocery store the other day with a cart full of stuff and realizing I forgot my wallet at home. Back when I had iOS this was a non-event with Apple Pay.
Now I'm standing there with a GrapheneOS phone in my pocket and a handful of apps that deal with the most advanced money the world has ever seen and I can't use the device to buy a sweet potato at a checkout lane 😮💨