LittleKernel or LK is an embedded kernel designed for small systems. page 
Prior Google-developed operating systems such as Chrome OS and Android, are based on Linux kernels, Fuchsia is based on a new microkernel called "Zircon", derived from "Little Kernel".
Gary Sims at Android Authority built Fuchsia from source page
The OS project Fuchsia is a capability-based, real-time operating system (RTOS) currently being developed by Google page
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To grok Zircon sits see Treble
Google's "Project Treble" will modularize Android to make updates faster page