It’s a bit more complex than that because for contactless payments you don’t share the card information with the vendor but an authorization token that need to be verifiable and certifiable by visa or mastercard.
So it needs to be sponsored in a way by visa or mastercard.
One can’t. If the corporations who handle your payments don’t support your app, it won’t work.
But the solution is simple: Don’t use software for something that doesn’t require it.
Slipping your credit card inside your phone case has the same effect.
It’s a bit more complex than that because for contactless payments you don’t share the card information with the vendor but an authorization token that need to be verifiable and certifiable by visa or mastercard.
So it needs to be sponsored in a way by visa or mastercard.
How would one go about creating a fully FOSS or mostly FOSS alternative to Google Pay?
One can’t. If the corporations who handle your payments don’t support your app, it won’t work.
But the solution is simple: Don’t use software for something that doesn’t require it.
Slipping your credit card inside your phone case has the same effect.