I'm in the process of doing both a Buster upgrade and image build on 2 Zero Ws.
I plan to do a bit of experimentation with each as neither board is my main setup (it still uses stretch)
At this stage I don't see any point in an image but if it's something you want to do by all means fire ahead. Most if not all, even the novice users have managed to grasp the concept of setting up a Raspberry Pi from scratch so the Buster fresh install I outlined is a breeze.
If you were so inclined you could alter one of the install scripts @bkenobi created to reflect the relevant Buster repos if so required. Maybe @bekenobi could expand on that.
Just so everyone is clear, there's a difference between a Buster upgrade and a Buster fresh install. Running sudo apt dist-upgrade from the CLI (command line) in Raspbian Stretch will indeed upgrade to Buster but it's not advisable to do unless you are very familiar with the Linux environment. The Buster fresh install and HG restore is the way to go.