Installing Podman on Proxmox is rather straight forward. The initial idea for how to do this came from a post on the Serve the Home (STH) blog: Create the Ultimate Virtualization and Container Setup (KVM, LXC, Docker) with Management GUIs. In that article STH uses Docker and provides a Portainer GUI. In this example the Portainer GUI is going to be omitted and use Podman instead of Docker. The daemonless part of Podman is the real selling point.
Installing Home Assistant on Proxmox is relatively straightforward thanks to a script by Whiskerz007 on GitHub. I will not detail the steps here as they are pretty well documented both in the README and on the Home Assitant message boards. This topic is about migrating the data from an existing Home Assistant installation into HassOS. The complication is that HassOS mostly has a read-only file system and for whatever reason SCP is not working correctly.