If you don't actually need all the drivers, you can use "make localmodconfig" to substantially reduce that. My local kernels build in 90 seconds on a 32-thread desktop machine :)
The kernel is a lot more stable than people think: I run the daily linux-next on my Debian stable gaming PC to look for bugs, and I don't find very many.
A stripped down cold build will literally take 90 seconds without caching on modern hardware.
The overwhelming majority of stuff that is being built is drivers, and most of them probably aren't needed for any specific user, so you can disable quite a lot of stuff.
Fwiw a full build of the fedora kernel config takes around 5-10m for my 12core ryzen 3900x, and it's definitely not the fastest CPU around.
{0}[calvinow@sousa ~/git/linux] git describe
v7.1
{0}[calvinow@sousa ~/git/linux] git clean -dffxq
{0}[calvinow@sousa ~/git/linux] zcat /proc/config.gz > .config
{0}[calvinow@sousa ~/git/linux] time make -skj32 tar-pkg
'./System.map' -> 'tar-install/boot/System.map-7.1.0'
'.config' -> 'tar-install/boot/config-7.1.0'
'./vmlinux' -> 'tar-install/boot/vmlinux-7.1.0'
'arch/x86/boot/bzImage' -> 'tar-install/boot/vmlinuz-7.1.0'
real 0m56.539s
user 18m41.863s
sys 2m8.754sIIRC, Debian has a command called "make-kpkg" which does nearly all the work for you, ending up with a installable package which works identically to the standard Debian kernel packages.
The resources behind your post likely have a larger carbon footprint.