[vially]

> Systemd docker-replacement on a non-systemd Linux would need to run in a VM, though.

Would it? There's no reason this hypothetical systemd-docker-replacement couldn't be architected in a way that would not have a runtime dependency on systemd-the-init-system.

In any case, I'm not even sure if systemd wants to be a docker replacement (although it does seem to pick up more and more container features lately). But there's definitely some overlap between the two projects (in particular around process/service management) but podman is a much more direct competitor to docker than systemd.