Apple storekit v2 real signed transaction info and real signed notification

Is there any real example of app store signed transaction or signed notification? I can find decoded form for transaction info or notification payload but not real signed example. There are some decoded examples - https://qonversion.io/blog/apples-2021-updates-to-managing-in-app-purchases-from-the-server but I want some real token with header alg and x5c. I would like test my backend implementation during development. My goal is receive App Store Server Notifications v2 and update my data.