In theory this would allow the nested systemd init to manage its own resources via slices and scopes - kind of like with LXC's nested mode but without the nasty security implication of bind mounting the real cgroupfs into the container.
Running a systemd container is not the only thing that this would enable - together with fuse-overlayfs it might allow one to run containers inside containers more securely.
The problem is that by default the nested group is mounted ro into the container which should not be necessary according to my research. It gets mounted rw as expected when userns-remap is enabled in Docker what is not desirable for me. I am not sure if docker/moby/containerd is at fault here or if it's a limitation of Linux control groups or user namespaces. It would be great if som
