In the past few years, the use of Linux in embedded devices has skyrocketed. Televisions, phones, automobiles, ATMs: you name it, it probably has Linux running in it. Linux is an open source platform,so we can view and verify it even from the kernel level.
As we are dealing with embedded systems we must integrate hardware and software according to our needs. So Linux provides the best option as we can even write basic kernel level drivers according to our requirements.