OCI is starting to be used for more non-container things like your describing actually. One example I'm aware of is the Helm tool in Kubernetes, which has support for using OCI as a method of storing/transporting helm charts (which are effectively just tarballs of Go templates/yaml). I

I think your challenge for virtualenvs would be that virtualenvs generally are not relocatable, as they hardcode absolute paths within the generated scripts (eg: venv/bin/activate`).