If you've got that experience under your belt, you'll be just fine. I haven't tackled zfs myself yet (I'm lacking the RAM, plus I was put off by the ECC RAM recommendation). But I know it unifies a lot of the things you're already familiar with under one roof (volume management and journaling) and adds more cool features (snapshotting, RAID, encryption, bitrot protection) without you having to combine and manage several different technologies (mdadm for RAID, LVM, LUKS, ...). I did that on my main rig and it turned out to be rather complex. Hence the switch to btrfs to at least squash a bit of complexity.

If you'd rather continue working with the storage technologies you know and avoid zfs, you may want to look into other OSs than TrueNAS (because that is zfs only). Two I'm running and can recommend are

• Open Media Vault: great for beginners (friendly, though dated-looking web UI), but Debian-based underneath and hence reasonably flexible if you know your way around the CLI, which you probably will. Case in point: mine is no longer just used as a NAS, but runs somewhere between 10-20 Docker containers, and I rarely touch the webUI these days.
• Proxmox: You mentioned VMs, so you're probably familiar with this one. I like its flexibility, allowing me to run each VM tailored to its purpose: a NAS VM for network shares, a hardened, minimal VM for publicly available services and Wireguard access into the network, an LXC as a local DNS server...