@Tippon That is a big part of the point behind containers, you don't have any long term state inside them. Migration is just a case of copying the configuration over along with the contents of any persistent volumes.
It's worth looking into Podman instead of Docker, the daemon-less architecture makes it more lightweight and secure as it's easier to have rootless containers. Management can also be easer as being a Red Hat project it integrates well into Systemd.
With your existing server on Xubuntu you may as well stick with Ubuntu Server or Debian for the familiarity.