To define custom VPC and images in Skypilot, you can use the resources section in the task.yaml file. You can specify multiple resources using the any_of keyword and define the cloud provider and image ID for each resource. Here's an example:

resources:
  any_of:
    - cloud: aws
      image_id:
        us-east-1: ami-xxxx
        us-east-2: ami-yyyy
    - cloud: gcp
      image_id: projects/xxx

This allows Skypilot to suggest cost-effective cloud options and pick the custom image and VPC based on the specified criteria.