My apologies, I misspoke: I wanted the image tag not to be $CI_COMMIT_SHA but to be a hash dynamically generated from certain files in the repo. The issue is that IMAGE won't accept a dynamically generated environment variable (passed from job to job via a dotenv artifact).
I think you could just jam anything you need in pipeline yaml from the dotenv file into outputs/variables then do something like this https://stackoverflow.com/a/71575683/2751619
