This maybe off topic, but the issue I have with many apps like Google Wallet, Samsung Pay, Zelle, and others is that they all sell your data to advertisers and share your data with "technical partners." They also never share who they are sending your financial data to. I propose that the FOSS community create a VISA like API that only collects fees from the largest users (aka big companies or someone who makes a ton of API calls) and donations from the community. This system should instantly convert crypto to fiat to be spent using tap and pay. I know there is already a company that does this but they are a for profit and will sell your data without a care in the world if it meant more money. This system only reports what is mandatory to regulatory bodies like the FCA in the UK or the SEC in the US.
It could work something like this:
1) It only supports Monero (XMR).
2) Each user when they create an account must also make a XMR wallet. Give the app (I will call it Secure Wallet or SW for short) access to the wallet. This wallet will act as a proxy for the user's primary XMR wallet.
3) The user must already have another XMR wallet or be willing to make one. This will be the user's "primary" wallet.
4) The user must send XMR from their primary to the proxy. Due to the fact that XMR is private this transfer should not be traceable back to the user assuming the user is using good privacy pratices. I won't list what the pratices are here, but lets assume the user does all of them to keep themselves private.
5) When the user wants to buy something they will use tap and pay and SW will instantly convert XMR to fiat and make the transaction. If the user does not have enought money the transaction is blocked.
No data will be shared with 3rd parties. If the government(s) come knocking asking for user data we can only provide the blockchain's records which is already public so it will be pointless to ask SW for any information. How the user obtains XMR is up to them. Maybe they have job got the money from an ATM, then traded the marked bills with friends a few times, then they use a crypto ATM that has no KYC or however else they have choosen to do it.