@arch I was doing this for a while with a TrueNAS VM running on top of proxmox. Done properly with an HBA and disks to pass through probably would've been pretty solid, except I ended up deploying it in a really unsupported way with the ZFS pool being a single virtual disk. The local-lvm where the vdisk lived was backed by a RAID-6 array from an actual hardware RAID controller, but it turns out running ZFS like this is a very bad idea lol. Started having really weird problems with various things in that VM after a while.
These days my TrueNAS setup lives on separate hardware though and not on Proxmox anymore.