Use the projects.move method to move the project to your organization. Update the billing account of the project to that of your organization.

Ensure that you have an Organization Administrator Identity and Access Management (IAM) role assigned to you in both organizations. Navigate to the Resource Manager in the startup’s Google Cloud organization, and drag the project to your company's organization.

Create a Private Catalog for the Google Cloud Marketplace, and upload the resources of the startup's production project to the Catalog. Share the Catalog with your organization, and deploy the resources in your company’s project.

Create an infrastructure-as-code template for all resources in the project by using Terraform, and deploy that template to a new project in your organization. Delete the project from the startup’s Google Cloud organization.