In Home Assistant, navigate to Settings > System > Backups. Configure the backup settings and create a manual backup.

On your new Proxmox server, you can download the qcow2 file from Home Assistant’s website and run it as a virtual machine.

On first boot, you can import your previous configuration from a backup.

This answer surprised me. Træfik (on docker or podman) uses the internal (container’s) port, not the external (host exposed) port.