You have been hired as a contractor by one of the travel technology company who is planning to containerize their existing applications in such a way that they can perform a lift and shift very easily

Cloud Functions is a serverless function platform that is highly vendor-specific, as the function code is directly tied to the Google Cloud environment, making it difficult to lift and shift to other clouds.

App Engine Standard is a Platform as a Service (PaaS) that uses Google's proprietary runtimes and infrastructure, which makes migrating applications away from Google Cloud challenging without significant refactoring.

Kubernetes Engine (GKE) is a managed service for deploying and managing containerized applications using Kubernetes. Containerization with Kubernetes provides excellent portability, as containers abstract the application from the underlying infrastructure, allowing for "lift and shift" to any environment (other clouds, on-premises) that supports Kubernetes, making it highly suitable for avoiding vendor lock-in.

Cloud Run runs containers, offering some portability, but GKE provides the full power of Kubernetes, including advanced orchestration, networking, and storage, which is generally preferred for complex enterprise applications requiring maximum portability and control over the container environment.