If you are trying to understand the difference between the different cryptography-related formats (PKS#12, PKCS#8, PEM, X.509 certificate, DER, JWK, BEGIN ENCRYPTED PRIVATE KEY??? 🤯), you will hopefully find some useful information here (and a lot more your did not wanted to know about).
Manually inspecting the content of a French COVID-19 vaccination certificate QR code. The main intent is to show with a concrete example which data is actually included in the certificate.