I watched the video posted by @stgraber on evaluating TrueNAS ( https://www.youtube.com/watch?v=ENrQ1RWKZuI ). I followed his instructions as a learning exercise. And I ran into the usual issue that most of us run into when trying to access a service on a virtual machine not on the home network but on the incus bridge network (incusbr0). So I created this diagram explaining how port forward rule works. Hope it gives some clarity.
Note: You can use an unused port number (32450 in my case).
Many Thanks to Trevor Sullivan for explaining how port forward rules work ( https://www.youtube.com/watch?v=vYK1aLSDVIw&list=PLDbRgZ0OOEpX_uqK_hAq98ltdc4DP-D34&index=8 ).
Would strongly recommend his entire playlist for LXD (Incus parent project) for beginners like me.