Today, growing a pool is possible by adding a vdev, right?
So, instead of RAIDZ2, one could setup their pool with mirrored vdevs.
However, I'm not sure about the self-healing part. Would it still work with mirrored vdevs, especially when my vdevs consist of two physical drives only?
If you want to containerise your apps, you could try Talos Linux. It is an api driven OS tailored to run Kubernetes. There is no bulk, only what is needed to run K8s, i.e., even no ssh server.
You control it with talosctl which calls the gRPC api endpoint to read or write all sorts of state including machine configuration.