I think there is a split screen example/tutorial floating about that could be helpful.
What you can do is use a canvas and paste stuff onto it. For performance the pasting is delayed till the frame draws, which leads to having to do juggling where you have to moving things into place, paste, and then wait a frame. At least last time I tried using it. Could have been updated since then.
Another probably simpler idea is to just have the tv be its own layer and you’d just need to change the scale/scroll offset to move the rest of the game to fit onto the tv. You could do that with some trial and error I should think.