I'm very much aware of Gentoo...but if you're going to compare basically any distribution is "poor man's Gentoo" because it's a collection of packages built from source files.
An ordinary Linux can be configured by installing pre-compiled packages. The system either has the package or not. Gentoo allows the package itself to be configured. Think of package ./configure arguments; they're abstracted as "USE flags" in Gentoo and allow tweaking the package internal configuration. It also allows modifying the environment variables used during the build. Setting CFLAGS/CXXFLAGS allows optimizing for the system's CPU instead of doing a generic x86-64 build.
Gentoo will give you that with proper package management including on the system part without having to do the weird dance you are making with abuild with a nicer experience if you want to patch and update your packages later and significantly better tracking on what you have done.
I have a hard time seeing anything starting from LFS which wouldn’t be better actually starting from Gentoo.