Zephyr has nothing to do with the Linux Kernel -- especially from a technical standpoint. It is a project that is under the umbrella of the Linux Foundation, that's all.
Sorry I didn't mean to suggest that its design took inspiration from the kernel. but adjacent features like Kconfig it does.
Much of the core kernel elements definitely follow Linux kernel conventions as well. For example the `eventfd` api was copied from Linux and is quite handy. The POSIX compatibility layer constants match those in Linux, etc. The style guide is also borrowed from Linux.
And then there is stuff in Zephyr like Devicetree, which is designed to look familiar to Linux users but operates in a completely different and broken manner.