The question wasn't about running docker on *BSD or macOS, but rather running some form of native container. Native containers don't rely on linux, they rely on the kernel having some form of containerization primitive.

FreeBSD has jails, which are a native type of container on freebsd.

However, BSD operating systems are really different from each other. OpenBSD doesn't have jails or anything too like containers, and macOS does have sandboxes (which are kinda like a container in some way), but no proper containers.

Docker isn't really related to the question of whether a native container solution exists on non-linux platforms.