A ladder my friend and lots of moving of stuff.

Depending on your budget I would suggest a wood/Laminate cladding on the entire wall. The TV unit or shelves below lintel level could be designed so that they stood out a bit. This would give you both a sense of a large wall, as well as separate the two spaces with grace.

A cheaper option would be a wall paint effect -- something subtle -- perhaps sponging. With your TV unit coming down from the lintel level.

Paint is your least expensive and most changeable solution. You have green in your artwork, and it looks like green in your kitchen (on my monitor anyway!) so I'm thinking either continue it onto this whole wall, or perhaps go with a yellow to compliment.

Yellow sounds great. But the pink on roofs of the inside rooms would be an issue. At least it looks like Pink from here. That would end up giving you 3 colors not in anyway complementary (or supplementary) for that matter.

So you would either have to get rid of the Pink. Or go with a combination of your existing Green and Pink. That would need loads of experimentation and a lot of luck.

If you chose to go with Green and Pink you might want to consider wall paper. It would be a little less experimental.

Lol, although the inside ceilings look pink, they are white.....and I am eliminating the green and going towards the browns and tans......but any artwork looks too small on that wall.

one story at a time