4
server OS with ZFS and webgui
(alien.top)
My suggestion would be Proxmox. It’s a full VM hypervisor with the ability to manage ZFS out of the box. I recently moved from a truenas VM to managing ZFS on Proxmox directly and the process was nearly painless.
Does TrueNAS Scale suddenly not run dockers?
Proxmox is great. It's Debian based, so you can install Docker directly on it if you want, but I recommend installing a Debian virtual machine and installing Docker there. That way you can manage backups, transfer the whole thing when you upgrade machines, etc.