You gave me the basic idea of how to do it.
First I used 3D camera tracker to create a 3D track of the entire scene(which I don’t end up using) then I roto out all my subject(in this case, it was just one layer)
Then I looked up, what are cards in Nuke and found out, I won’t be needing those as I will be projecting the rotoed layer onto a separate footage.
I saw tutorials on how to animate 2D images into 3D space using PS and AE and that gave me the rest of the missing links that were needed.
So in the end, I didn’t do much at all. I just made my rotoed layer 3D, changed its 3D orientation a bit, made a camera layer, raised its height a bit, and boom… it gave me the result I wanted.
So thank you sir, your instructions genuinely helped me.
p.s- the rotoed layer is from the minions movie, illumination studios rendered almost all the minion scenes from their eye level, so I couldn’t actually re-shoot.