There are many CI/CD solutions on the market, basically none are open-source.
Additionally, each define their own format, usually in YAML, that specifies the tasks, their dependencies, and how they should run. Also lifecycles (pre_start, after_task, &etc.).
Develop parsers to take any of the popular formats—e.g.: Travis CI, Circle CI, Gitlab—and read it into a common struct.
Write CI/CD platform that works with that struct, and executes those tasks in the chosen environment (Windows, Mac, Docker, Docker Compose, Kubernetes, native Linux).
Thinking to implement it in Rust with serde. Something like:
Needs to be able to go to—and from—each format. Validating each config against the rules of the standard implementation would be a nice-to-have.