For what it’s worth: I did upgrade right away. I experimented with LXC, saw that NVMe latency for my database still sucks on ZFS (not surprising tbh), and put the experiment on ice. I may try again with Goldeye and DirectIO, and whatever flavor of LXC is production-ready then.
Apps have been fine. They worked on k3s and migrated over to Docker. No complaints there.
LXC is a little mad, but useful for this particular, more complex Docker app. Only because TrueNAS is an appliance, and so running random Compose things with a bash handler script doesn’t fit well into its app paradigm.
VM is sheer lunacy. I’m sure there are apps that run best in a VM instead of a container - it’s still lunacy. Why in the century of the fruit bat are we still using full virtualization? Rhetorical question.