Someone I know has been playing around as well: https://github.com/fproulx/shc-covid19-decoder .
He also has a piece of code to validate the digital signature with the government public key: https://github.com/fproulx/shc-covid19-decoder/blob/main/src/shc.js#L21
Also another blog post from someone else I saw shared around: https://marcan2020.medium.com/reversing-smart-health-cards-e765157fae9 (There’s an interesting notebook referenced at the end with steps to parse and create Smart Healthcard).
Can’t wait for a cryptocurrency powered by proof-of-vaccination :D
Some US states have a vaccination lottery. Basically the same thing, really.