Helm really solves a different use case than this.
This is about describing the desired coordination among running containers. Helm is about how you template or generate your declarative state. You could certainly add this description to your templates with Helm, but you couldn't actually implement this feature with Helm itself.
I bundled both composition & orchestration under the same header.
It so happens that pods have multiple containers, which is another example of Kubernetes having a specialized specific composition or orchestration implementation. One that started as composition, and here iterates towards orchestration.
This is about describing the desired coordination among running containers. Helm is about how you template or generate your declarative state. You could certainly add this description to your templates with Helm, but you couldn't actually implement this feature with Helm itself.