similar projects

https://www.insentricity.com/a.cl/283
https://github.com/yeokm1/gentoo-on-486
https://github.com/MiSTer-devel/Main_MiSTer/wiki
https://yeokhengmeng.com/2018/01/make-the-486-great-again

alternatives to "standard" Linux:

ELKS linux-i386 for 16-bit
Minix
NetBSD

https://www.kernel.org/doc/html/latest/x86/boot.html
https://0xax.gitbooks.io/linux-insides/content/Booting/linux-bootstrap-2.html
https://www.kernel.org/doc/html/latest/x86/zero-page.html