Backing up my PARA folders with TrueNAS and BorgBackup

I am preparing to move from Debian 12 Bookworm to 13 Trixie, and rather than do a straight upgrade, I like to take the opportunity to wipe the machine completely and start afresh. This is prompting me to do some overdue backups, so I can pull everything into the new OS when all installed. These instructions are for backup of my PARA folders only - that's Projects, Areas, Reference and Archive folders. My media is handled separately. For now anyway. This is a learning curve for me. All my backups in the past has been dumping things on external usb hard drives. I'm still a way off anything robust like a 3-2-1 backup strategy, but I feel like I'm making some steps in the right direction. I have a TrueNAS operating system running on a Supermicro server, housing 4x 4TB hard drives (overkill, but futureproofing). My media is already stored there on a different dataset. Rather than doing my usual slow copy of my PARA data to a couple of external hard drives for an OS upgrade, I thought I'd…