The next service I added to my Proxmox was OpenMediaVault (OMV) in a virtual machine rather than an LXC. LXCs are great, lightweight containers, but they use a shared kernel and don't have the level of isolation you get from a VM. I also wanted to easily pass hardware through to the VM to allow it to control the USB ports on my machine to give it the ability to directly control my external drives.
There could be a strong case made that I should have installed OMV first and had it controlling the media containing my .mkv files served by Plex. And if I were to sit down and build it all out in a weekend, then that would surely be the way I would go about it. However, it was a few months after my initial setup that I got around to setting up a NAS.
When my server lost a drive (RAID 0, so total data loss but I did have backups) and I installed replacement drives I dedicated one to OMV and redirected all backups to it. It wasn't hard to do, I was able to do it all using directions found on the Proxmox site.
I have since opened up NFS, SMB, and FTP shared directories. I then added Veeam Backup agents on my desktops and laptops with OMV as a backup target.
Thank you for following me on my journey, please feel free to reach out to me if there is anything you want me to dig into more.