I recently had to increase my proxmox storage as well from an old 256 to 1TB. What I did was make a copy of /etc via PVE Host Backup and saved that on my NAS/external storage. Almost everything is in /etc/pve. Then I created backups of all the VMs and stored those on the same external storage. I then installed proxmox as normal and compared configs between backup and new configs then restored VMs from backup. The reason I did it this way is because 1) I had installed proxmox a while ago and new config > old config for stability after adding some necessary PVE scripts (e.g. intel chip, and 2) I’ve had weird issues before cloning drives and a fresh install was easier than risking some weird edge case troubleshooting. It also let me keep the old SSD as a backup in case something went wrong.

Edit: Also recommend going with zfs mirrored on the new install during the setup: target disks options and zfs mirrored. ZFS offers some benefits vs the default lvm.

Absolutely no problem with it being virtualized as long as you have a pci storage controller and pass that through to trueNAS. HBA cards can be found that do this without raid or anything so you can use zfs in trueNAS.