For certain US states SHC (Smart Health Card) format vaccination QR Codes are available from the state government (such as California) or a 3rd party (such as MyIRMobile: https://myirmobile.com/). The Canadian provincial QR codes are all now to the Federal standard in SHC format, so there is a high likelihood that the WestJet upload and extraction of the name and vaccination status from an SHC QR code will work for non-Canadian codes too (possibly including EU ones that are also to the SHC standard).