Unfunded is kind of a stretch, but at least libxml2.
Essentially "povertyware" as you call it when you consider the trillion dollar companies built on top of them? Now that's way easier: SQLite, PostgreSQL, ffmpeg, imagemagick, numpy, pandas, GTK, curl, zlib, libpng, zxing or any other popular qr/barcode library, etc...
I'd say the Gentoo handbook comes pretty close. You set up everything in the system and all is well explained. Not quite as extreme as LFS but enough to learn and not punish yourself.
Even worse. On MacOS the scrollbars are invisible by default, and only appear while you scroll, plus a second or so after stopping.
So to grab a scrollbar in MacOS you first have to scroll the document to make the scrollbar appear. Then you have under two seconds to move the pointer on top of the narrow scrollbar so it expands allowing you to grab it before it disappears again.
My mileage was quite different: last time I tried, scrolling too fast with the mouse wheel consistently caused a segfault.