Install kubernetes on debian stretch server without systemd
Since you are well off the beaten path, you can probably just run things by hand with k3s. It's a single executable AFAIK. See https://github.com/rancher/k3s#manual-download as a simple starting point. You will eventually want some kind of service monitor to restart things if they crash, if not systemd then perhaps Upstart (which is not packaged for Deb9) or Runit (which itself usually runs under supervision).