Have you perhaps looked into the DORA metrics?
Through six years of research, the DevOps Research and Assessment (DORA) team has identified four key metrics that indicate the performance of a software development team:
- Deployment Frequency—How often an organization successfully releases to production
- Lead Time for Changes—The amount of time it takes a commit to get into production
- Change Failure Rate—The percentage of deployments causing a failure in production
- Time to Restore Service—How long it takes an organization to recover from a failure in production
Btw: For the whole delivery, not testing only.