FTA: “Before deleting systemd, need to be sure that OpenRC will be installed, to so the command will be

  sudo apt purge --allow-remove-essential systemd && sudo apt install openrc sysvinit-core

I don’t see that installing openrc before deleting systemd. It tries to delete systemd and, if that fully succeeds, to install openrc.

> Issue itself was that while uninstalling systemd somehow OpenRC was removed too or not installed at all.

I don’t see how “somehow OpenRC was removed” could be true if it wasn’t installed before. My hunch would be that uninstalling systemd failed halfway through.