Although Microsoft's former CEO, Steve Ballmer, called it a few years ago nothing less than "a cancer," Linux is now at the core of an IoT solution that comes from Redmond. Azure Sphere includes microcontrollers, a cloud-based security service, and an operating system that includes a custom Linux kernel.
https://www.notebookcheck.net/Microsoft-launches-Azure-Sphere-its-first-product-with-a-custom-Linux-kernel.299354.0.html