Given you referenced less is more, the opening + shelves + photos will be very busy. I can see an earthy color grasscloth and some clay pottery on the ledge, bringing the eyes down away from the opening.

Maybe decide on the fireplace later, but I think it could really look good just painted black.

the pass through open area is very distracting. It is part of the visual on the dining side.

I am guessing you don't see that as part of the visual.

I think you need to consider what is existing. Or cover it over with a large framed piece.

If you want a photo gallery wall, then eliminate everything on the shelves in the kitchen, that is fighting with your vision.

I would clear the space, limit the things on the shelves on the fireplace side... 3 things on each shelf. only things that are treasured and work together. google shelf display ideas...

One large piece above the fireplace, and a statement piece on the buffet/counter.

Some options

Close up the pass through and hang a great piece of art you have busy tiles on the FP IMO please no gallery wall on tat wall and honestly the shelving is kind of lost . If not closing that pass through the plants are an awesome idea.

Since that opening doesn't look like it serves any purpose, I would build a shallow cabinet from the cupboards below to the ceiling to enclose/cover it. It could be the same wood as the lower cabinets or painted to match the wall. If it interferes with the open shelving, then think about filling that whole area with shallow cabinets. Then add some art to the right of it closer to the railing.

Maybe not glass, but a configuration like this:

Great ideas thank you, nothing like Houzz to open my eyes and give fresh ideas!

The pass through is useless from this side yes, but from the other (kitchen) side it gives light (kitchen is a bit dark) and gives a feeling of connection/open-plan.

I will declutter a bit and get more statement pieces. Will update.

Do you think a rug under the table can work?

Agree with closing up that opening, way too busy. Address lighting in kitchen if needed.

Gallery walls are always more so you wouldn't be happy with that. Not sure people understand ya don't SNAP your fingers and close up an opening in your wall. Maybe a simpler wall paper would be less is more.