Getting image digest after push

Description

Typically users rely on the Aux field to get at the digest following a successful push using ImagePush. Specifically, something like this can be done on the caller side, note the unmarshal into types.PushResult:

if message.Aux != nil {
	var pushResult types.PushResult
	if err := json.Unmarshal(*message.Aux, &pushResult); err == nil {
		imageDigest = pushResult.Digest
	}
}

However, in some scenarios (when containerd image store is enabled newer cli versions), the digest is returned in the Status as a plain string. And afaics the only way to get at the digest is to parse this raw string?

https://github.com/moby/moby/blob/f9522e5e96c3ab5a6b8a643d15a92700ca864da6/daemon/containerd/image_push.go#L126-L133

So, the question (or feature request), is it possible to standardize on a convention for getting the digest when reading from the io.ReadCloser.

I believe this request is in the same vein as https://github.com/moby/moby/issues/46528, but specifically for push.

Start with pkg/jsonmessage/jsonmessage.go and daemon/containerd/image_push.go, then compare the Aux-based caller example with the Status response described here. Review issue #46528 for related API context. Done means defining and documenting a consistent way to obtain the digest from ImagePush output across both response paths.