I'm trying to create a 'fake' window on a starship bridge by having it be a portal to a camera that is attached to a smaller model of a ship so I can animate that ship to give the illusion of movement for the player(s) inside the ship without having to move all the assets and moveable parts.

However I'm running into some problems trying to get this to work. The closest I've come is a short tutorial on depth maps found here: https://www.youtube.com/watch?v=r5XAVy6wE-A [1]

But I can't seem to get it to work, at best it just creates an invisible material. Anyone able to decipher the tutorial in some easier steps or have a different idea altogether to create the effect I'm looking for?

For reference I've tried using a live feed from a camera to a texture, but it's too obvious it's displayed on a mesh instead of having the depth and other subtle hints looking through an actual window gives.