Fly.io has introduced Fly Machines, which are VMs with a fast REST API that can boot instances in about 300ms. The platform allows developers to manage individual VMs and create cost-effective applications that scale to zero when not in use. Fly Machines are designed for quick starts and stops, making them suitable for building functions-as-a-service (FaaS). The API is built with efficiency in mind, reducing infrastructure latency and ensuring fast boot times. While there may be some limitations due to hardware pinning, the overall design aims to provide simplicity and reliability.