Comment by icedchai

Building a microkernel based OS feels feasible because it’s actually quite open ended. An “OS” could be anything from single user DOS to a full blown Unix implementation, with plenty in between.

Amiga OS is basically a microkernel and that was built 40 years ago. There are also many other examples, like Minix. Do I think most people could build a full microkernel based mini Unix? No. But they could get “something” working that would qualify as an OS.

On the other hand, there are not many C compilers that build Linux. There are many implementations of C compilers, however. The goal of “build Linux” is much more specific.