Google Wallet is not so much a "wallet" for your cards but a way to link your cards to their own payment service, Google Pay.

Both Apple and Google had a lot of problems convincing banks to accept their respective services, and even then many stores still don't support this payment method. A company with the clout and size of Proton has no chance to get their own service widely accepted.

The FSF (and RMS himself) wanted an alternative for online payments for ages, without crypto. An anonymous buffer layer between your payment method, like a credit card, and the vendor. I believe something was eventually released but it never took off, because unlike something like a NFC Wallet, vendors would have to natively support GNU's version.

Same, if they made a wallet for cards then I'd actually use my phone to pay for stuff

I started using Curve since I swapped to Graphene. Upsides: it's not google and it works fine. Downsides: it's a free as in beer app that (I assume) is selling my data.

I've read that Monzo used to have their own NFC payment app, but it looks like that isn't around anymore and they just integrate with Google Pay now. If anyone knows more about it I would love to hear it.