Not a single mention of elastic beanstalk or App Engine? The best middle ground for small teams who just want one reliable website with minimal scaling (and who can't just choose a nom-aws service).
Do you have any examples of non-proprietary solutions?
Knative + buildpacks is one. CloudFoundry is open source too (although CF now runs on Kubernetes I think)
Cloud foundry offers their old(er) architecture as well as 2 ways to get the “cf push” experience over Kubernetes. Check out KubeCF and cf-for-k8s. Both of these are open source projects that you can deploy to a Kubernetes infrastructure of choice.
[1] https://github.com/cloudfoundry-incubator/kubecf [2] https://github.com/cloudfoundry/cf-for-k8s