What is the problem you're trying to solve
On can easily push all images involves in a Compose application, but still need to find another way to share the compose.yaml definition.

I suggest we define a mechanism and media type to push a compose.yaml file to a registry, in addition to images, with adequate OCI references

Describe the solution you'd like
Push Compose application as an OCI artifact.
We would use:

• application/vnd.docker.compose.application media type for the whole compose application
• application/vnd.docker.compose.config+yaml media type for the compose.yaml model
• OCI or Docker manifest media type for referenced images

{
   "schemaVersion": 2,
  "mediaType": "application/vnd.oci.artifact.manifest.v1+json",
  "artifactType": "application/vnd.docker.compose.application",
   "blobs": [
      {
		"mediaType": "application/vnd.docker.compose.config+yaml",
		"digest": "sha256:.."
		"size": 123,
	  },
      {
         "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
         "digest": "sha256:.",
         "size": 123,
      },

Mechanism to push/pull such a manifest is our of the scope of the compose-specification, but for illustration this could result into something like this:

$ docker compose push --application registry/foo/bar
[+] Running 3/3
 ⠼ Pushing foo: xxxx Layer already exists                                                                         2.4s
 ⠸ Pushing compose.yaml: xxxx                                                                                         2.4s
 ⠸ Pushing compose application: xxxx                                                                              2.4s

$ docker compose --application registry/foo/bar  up 
...

Additional context
This somehow resurrects the main concept of Docker App