Like the other commenter said, this is the kind of thing custom distros always have to do, that lead to either reinventing or just going back to a big fat distro. I've gone around this wheel a couple times. It's a nice idea to have something custom-tailored, but a tailored suit only fits one person, and is expensive.
You can still build a system to manage Kubernetes nodes without making your own distro. Even a heavily modified stock distro gains you benefits from basing off someone else's work. You can reuse the solutions they've made, and contribute back your customizations for your specific use cases.
That's how today's distro installers/package managers/etc came to include all the functionality they have. You couldn't eject a CDROM from a Busybox system, until one weird kid in high school decided to try to use Busybox to make a CD-bootable RAM-resident distro, found out it had no 'eject' command, and then sent a patch in to Busybox to add it. Now everyone can use that command, and that functionality is still there 20 years later.
It's also a lot harder for users to use proprietary solutions than ones they're familiar with. Your OS has no shell or console, only an API? So if there's a problem, how do I drop in with gdb, strace, tcpdump, and the entire suite of Linux debugging tools, to try and quickly diagnose and then patch an issue? I'm sure you've created some way to do it, but now I need to go find out how to do it, and probably use whatever stock tools are there, which may have their own quirks or incompatibilities.
But I get that a corporation's interest is mostly in "get something working now" as opposed to "get something working that will be better in the long run". DIY/NIH often becomes the engineering department's watchwords, and a custom distro is one of those eventualities.
