Windows Update is back on the Start menu, above Programs, and it works the way the page did: Welcome, Product Updates and Support Information down the left, the globe in the banner. Welcome shows what you have, checks the release list when you click Check for updates, and installs a newer version when you click Install -- in a terminal window in front of you, asking for your password there. Running from a source checkout, it pulls and rebuilds that checkout instead. Product Updates does the same for the rest of the computer: the distribution's packages through apt, dnf, yum, pacman, zypper, apk, xbps or emerge, plus Flatpak and Snap, with a count of what is waiting and one button to install it all. Nothing is ever checked or installed on its own.
The README now has an Updating section with the three ways: from the desktop, from a shell as root with curl -sL jacktulli.github.io/w2k | sh, or from a source checkout with git pull, make and sudo make install.
curl -sL jacktulli.github.io/w2k | sh