Make OCI _edge tag name configurable when pushing to a registry

Launchpad can push OCI images to different registries. It always uses the _edge tag but that's not sufficient for some cases.
In my case, I want to use launchpad to push to the AWS Marketplace (which has a registry per marketplace container product) but it's not allowed to reuse an already available tag (tags are immutable on that registry).

From the docs (how to push):

Note: AWS Marketplace ECR repository tags are immutable. So don’t use “latest” tag or leave empty tag.

That means I can't use launchpad for pushing images there. Making the used tag name configurable (during build time) could solve that problem.