w3c payment processors

I would like to implement a payment processor in line with the w3c payments
spec

I was wondering if anyone else is working on something similar because I'd
like to test payments from one processor to another, and it doesnt seem
clear how to do that right now.  Perhaps with some running code the problem
would be easier to break down.

Just trying to establish tentatively if anyone may be willing to help test
in the short to medium term.