That could help you in applying your new C skills in writing a simple device driver/kernel module you can play with. If are really into low level stuff I would propose an Arduino board whose OS is minimal, the Linux kernel is already very complex.
Get a role in an embedded software company and you may learn it all, but some experience is required.
I dont mean creating a whole functional module, but more like using an example, modifying some values, adding it to the kernel and compiling.
To build a module you don't need to build the kernel, but you do need the kernel headers, you will understand all this once you get to understand a bit of C language, and a bit of assembly won't hurt. Start with MIPS.
You do need a good grasp on the C language, and a lot of time.
If you can drive the command line and a makefile you should be able to tinker, and render it unable to boot. :)