I don't think anyone here ever went with bitbake, but I did notice that file, and that it pointed to a wonderfully outdated yocto tag

.
FWIW, the current link for that is probably on
https://www.yoctoproject.org/softwar...ived-releases/
People building a whole bunch of stuff have gone with BuildRoot in the past, but I've personally only ever used crosstool-ng and then basically scripted stuff myself.
If you only need a TC, and not actually a giant "build-me-a-distro" machinery, c.f.,
https://github.com/koreader/koxtoolchain which is basically a frontend to my setup.
If you intend to build kernel modules (and only modules), you *may* need something using a GCC version closer to what's used to build your device's kernel. I personally don't have a config for that on Kindle (but I do for Kobos).