Yes.
(Although I’m currently dealing with an issue)
I’ve successfully tested nested truenas (truenas vm on truenas vm on truenas bare metal)
For “testing” purposes it’s fine. Don’t use it to store data you care about.
You make two zvols for disks (I prefer to pre-create the disks as sparse images)
You want 32GB for the boot zvol and then whatever for the pool.
You need 8GB of ram for the VM, 16GB if you’re nesting again.
I use virtio for the Nic and disks.
Just select the truenas iso as a cd. Install. Then remove the cd.
When you make your single disk pool, you will see a warning. It can be ignored as long as you don’t care about the longevity of the pool