Linux From Scratch (LFS) is a type of a Linux installation and the name of a book written by Gerard Beekmans, and as of May 2021, mainly maintained by Bruce Dubbs. The book gives readers instructions on how to build a Linux system from source. The book is available freely from the Linux From Scratch site.
Mainly it's just compiling, so not really educative Gentoo Wiki is a better resource, especially the dev manual and the time could be spent on contributing to it, instead of compiling everything yourself manually
https://www.linuxfromscratch.org/lfs/downloads/stable/.