I just built a balenaOS image from the balena-os/balena-raspberrypi source and I found this page really helpful.
The only problem I had was configuring the image after it was built so that a flashed device showed up in balenaCloud. Eventually I found a comment in the forum that pointed me towards the balena-cli os configure
command which was exactly what I needed.
I think there should be line at the end of the “Bake your own image” section of that balenaOS docs page that links to the command documentation.
Thanks for the documentation. It made building an image from source pretty straightforward.