Also, while the details of the vaccination are contained in the payload, the app displays only the bare minimum of data to the user: verified vaccination status, and the holder's name to compare with photo ID (required in BC for adults).

I appreciate that the data contained in the code is as minimal as it can be, while the official app is displaying even less. Working off-line should keep it reliable as well, since it does not make or require server calls. This too would be different from Portpass, since it apparently stopped working.