As if you dont need nodes, pods and a runtime for Nomad.

An ex-colleague “sold” us developers nomad once as an easier, better alternative to k8s. They used exact same arguments, and we ended up with Nomad for our test and staging environments. It was such a mess, while it covered basic “run this” scenarios fine, nothing like kustomize or helm for nomad existed back then (I doubt it exists now). The tooling was non-existent, neither were good practices or recommended setups - nobody seemed to know how to tie it into a ci/cd setup without a bunch of bash scripts to get basic stuff like templating working. Implementing any kind of edge case or a tricky requirement felt like we are doing breakthrough work since no documentation, guide or SO page covered anything but “simple setup of your nomad cluster in two steps” - nomad is simply not popular enough. That experience made me swear off any unpopular but “trust-me-bro-its-actually-good” software.

Sorry for the rant, your post made me remember how pissed I was at our tech stack back then.

Meanwile no one offers Nomad managed service, so who create those clusters, who operate them, who keep security / upgrade on...?

You go to any cloud provider they all offer managed Kubernetes solution.

If you're running it on your own setup it gets complex. However half the concepts you listed exist in Nomad also, like the container runtime engine.