I would not cover the mirror or window above the fireplace if it is built-in. I would put a TV there only if there is a regular wall. The right side is your only option otherwise. That room is beautiful!!! There si nothing wrong with putting a couch in front of a window. Pull it out 1-2 feet from the window though. Put a blanket ove the back to prevent counch from fading. You could even put a skinny long table behind the couch with plants on it. I would add one side chair angled toward the fireplace on each side of the couch but forward more with a shared coffee table and end tables.

If you want real help, then provide a floor plan with all dimensions, including doors, windows, etc.

More pictures from all angles are also helpful.

Why not show photos of the missing wall with the fireplace?

A few dimensions would help.