I learned a bit of rust and wrote a minimal init system perfect for my use case: https://github.com/distrust-foundation/EnclaveOS/blob/master...
The init system is statically compiled into the kernel as a CPIO.
This is about as bare bones as you can get with linux, and may help others understand the essentials.
I was only able to do this because of years of running gentoo and building linux for various embedded projects. It pays off!
You could swap out my init binary for busybox init and have built a full interactive linux distro from scratch in under an hour.