obviously debian has a console (minimal) version, without gui. You can try that too, just I don't understand what are you looking for.

Possibly, but would entail a fair bit of work, I'm thinking.

When you talk about using a build process and code from other projects it may apply. Actually using other projects does not.

All Linux distributions consist of system utilities and user space applications from the GNU software collection layed onto a Linux Kernel with the module collection compiled for it, then with an added GUI overlay and configuration. If you want a kernel and shell combined so you do not need all of that you can only combine certain small portions of things while stripping out what is no longer needed because you will not be using those applications, modules, or services (or have them built into your new kernel mashup).

It sounds horribly messy, but doable. Success will require that you carefully consider each piece and simplify wherever you can. All of the structure that applies to enabling or securing a shell, for example, becomes useless when the shell is built in. PARTS of the process scheduling will still apply, but some of the rest becomes questionable. The entire user-space separation code becomes useless with the user already WITHIN the kernel.

You might almost better start with your own kernel.

Of course! I can send in some results if of course I have successfully done it!

Great! Have you a GIT repository where we can download and examine the code? I would like to examine this OS in a kernel for myself, and I wager many others would as well.

That's the most difficult part, to bootstrap the Linux Kernel with some appropriate software to make it boot into an "OS" (whatever software you manage to bootstrap). Then you'd need to be able to expand the OS after that, with buildtools.
Alot of distroes skipped this step (bootstrapping), by forking another distro.

But, generally the Linux Kernel comes with the GNU operating system and GNU tools and bootstraps into those. Alot of bootstrapping is now done with Busybox, due to ease. But it comes with no buildtools and no option for that, so you'd have to build externally for it.

PS. There are various options in the Kernel for how to bootstrap, where the default is /sbin/init (you could try booting into /bin/bash)

Ps2. The most modern and hands on approach, I think you can get with Gentoo. They don't really do it anymore, they skipped to "stage3" installation, but previously they had "stage1" and "stage2" installtions as well. That's probably not exactly bootstrapping, but "stage1" would be good experience to get a better understanding. Stage 1 Gentoo installations are still available I think (but generally not used).

Ps3. You could use a virtual machine environment to test these things.

Just punting here, but working up a set of external "utilities" to run from your unified operating system might just conflict with the goal of building the operating system into the kernel in the first place. One cannot avoid the entire GNU app collection by reinventing the entire GNU app collection.