You're right, it's very much a trade-off and preference where you put control, NixOS or Kubernetes. I'm not so much torn, but more believe you always have to weigh pros and cons.
For CoreDNS specifically, this setup adds CoreDNS to every node, and every node does DNS locally, so there's no redundancy benefit to using a Kubernetes deployment for CoreDNS. It does become a benefit as soon as you can't have a CoreDNS per node. I guess the obvious downsides to CoreDNS per node are that cache becomes very spread out in larger setups, and you may end up hammering your API server and upstream DNS servers more.
You're right, it's very much a trade-off and preference where you put control, NixOS or Kubernetes. I'm not so much torn, but more believe you always have to weigh pros and cons.
For CoreDNS specifically, this setup adds CoreDNS to every node, and every node does DNS locally, so there's no redundancy benefit to using a Kubernetes deployment for CoreDNS. It does become a benefit as soon as you can't have a CoreDNS per node. I guess the obvious downsides to CoreDNS per node are that cache becomes very spread out in larger setups, and you may end up hammering your API server and upstream DNS servers more.