IOx sandbox is a general purpose linux virtual machine that runs IOx application hosting framework and services. It is meant to be used as a playground environment by developers to get acquainted with IOx framework, developing applications for IOx etc., The sandbox is essentially a simulated environment and doesn't support peripherals (USB/Serial etc.,) and services that may be only available on real IOx devices.
This sandbox powers the IOx Devnet experience.
You can experience the sandbox environment on our Devnet site