The golang example where he uses scratch as the base image is essentially this.
https://github.com/opencontainers/image-spec/blob/master/ima...
But this is our flow too. We have a jenkins job that builds our master branch and uploads deb packages to jfrog. And then another to create a GCP image with these psckages, and a third to actually deploy these images to GCE. Containers are used for the various jenkins jobs, but not on the actual GCE instances.
In a previous incarnation I wrote https://github.com/regularfry/au to take the grunt-work out of packaging up ruby apps, and pretty much all it does is generate the minimum set of files that `dpkg-deb` needs to spit out an archive.
Reminder: the Debian Packaging Guidelines are meant for official Debian packages.
Making a package with dpkg-deb -b <dir> <packagename> is very easy and gives all the features of APT (dependency tracking, config management, atomic deployment).