Containerd is just one part of what Docker does. There is also image management (signing via Notary), distribution (pull/push to the Hub), orchestration (Swarm

Containerd is just one part of what Docker does. There is also image management (signing via Notary), distribution (pull/push to the Hub), orchestration (Swarm and friends), linked services (Compose), etc. You could reuse all the rest of it while running containers in FreeBSD jails as the method of containment.