They announced this new app this morning to replace COE.
Essentially you will still upload vaccine certs, insurance, etc. to a site, then when they've verified it they will send you an email with a QR code.
It looks as if scanning that code ties your documents to the app which you can then flash on arrival.
I *think* that's how it's going to work, but you decide. It could equally well be a new version of "Red Light, Green Light".