Definitely an old article but a lot is still moving along in the DoD cloud native space. The article mentions Platform One, which has done a lot to provide open source resources for those using k8s within the DoD community.
There was a decent number of people who left Platform One and started Defense Unicorns. If you are interested in disconnected k8s deployments, checkout their open source project Zarf. - https://zarf.dev/
They also have an interesting OSCAL compliance through kyverno project called Lula. - https://github.com/defenseunicorns/lula