Why bother with another Android app when the HSE COVID-19 app works already?On Android phones, download the free app Greenpass. For iPhones, go to the free web app Covid19passbook.netlify.app on your phone’s Safari browser. This will do the same thing as the Greenpass app, with the added utility of letting you ‘import’ the QR code from a photo on the same phone (just screenshot the QR code from the email on your phone).
And how does one know that the apps that you mention are trustworthy?
Anyway, Brendan asked specifically about importing the vaccination cert into his Apple iPhone Wallet and that is not possible unless/until the cert is wrapped into the required pkpass format. I've seen sites that claim to do this but have no idea if they are trustworthy.