Backing up Proxmox to TrueNAS

There are lots of solutions to back up virtual machines on Proxmox, but surprisingly little that I found to back up the host–until someone pointed out to me that I could use ZFS replication. Documentation on doing this to or from a non-TrueNAS host was somewhat lacking, so here’s what I wrote up. The same principles would be broadly applicable to any other Linux (or likely *BSD) system.