TrueNAS CORE with SCALE using Debian
The current TrueNAS CORE 13 will be iXsystems’ last FreeBSD-based NAS. From now on, you will see the operating system of popular NAS software moving to Debian, but this is necessarily bad news unless you are a FreeBSD enthusiast. Using the OpenZFS file system means you can migrate in-place to a new operating system, although this is a one-way transition. But there’s a small problem, the VM appliance won’t be migrated along with your data.
The TrueNAS CORE plugin runs in a FreeBSD jail and the new version will use KVM with the Linux kernel built in. Unfortunately, there is no way to move a virtual machine from one to another. TrueNAS CORE 13.3 will have a final update with fixes for ZFS and Samba to match TrueNAS SCALE, so you have some time before considering migrating.
Register lists some other desired features in TrueNAS CORE 13.3, as well as some details on the timeline that you should pay attention to.