Is this possible? Forgive me as I am new to docker and how it works.
You can start different images (debian, arch linux, centos, …). You just need the base image or another image from Docker Hub.
It’s possible to run xorg / fluxbox inside a docker container @ RancherOS 
Testted it with a Alpine container, but experienced some problems for example with Chromium (sandbox, namespace, …).
Tried to build Alpine isos in the past using stock scripts with no real luck. Do need to read up more on Docker and Rancher. Arch is of course systemd based so would need a lot of setting up to get running.
Are there guides on using docker hub?
A docker container is not a full running OS instance, typically only run one process. So I think systemd is inrelevant here.