Maybe. But Windows 10 already supports multiple monitors and monitor switching. I suspect that the iMon/LCD architecture wouldn't support the LCD being treated as a monitor anyway. Plus changing from a large screen TV to a small resolution LCD monitor could cause all sorts of resolution switching issues.
But if what the OP asked for was actually provided, what would the display be used for, and how? I'd be interested to hear the Use Case. Because knowing that the highlight is currently on"Video" and I could move it down to "Movies" wouldn't help me much, because from there trying to display a list of movies on the LCD would be problematic, I would think, unless a whole new display method was used. If a user really knew the menu structure off by heart, I guess they could navigate to the Menu List View, and then scroll down the list, but then what? The TV is off, so the movie can't be played. It would be easier to turn the TV on to navigate. There would be similar issues with Audio as well. Even navigating to an Album or Track, or Playing Now, would be problematic. Adding tracks to Playing Now wouldn't be a good process.
So I'm wondering why this is really required, and how it would be used? Not that I can do anything about providing it!