You won't find FOSS.
There are alternatives to Google Pay on Android however. My bank (a "Sparkasse", German government-owned bank) has its own mobile payment app which appears to just simulate a Visa/Mastercard's NFC chip. IME it works pretty much on any terminal that accepts physical contactless cards.
Banks have much stricter privacy policies by law and I need to accept their terms anyways.
That isn't really an argument for EVs but rather an argument to build a train stop near them ASAP.
EVs are an interim "solution" at best in the vast majority of cases and the majority of resources should flow to the actual solution instead which is not the case in the slightest.