Can you add more nails to better attach the VJs to the studs behind? Or use a smaller strip of wood?

You have a few options here to make some big improvements. 1. You could remove the wall that has the doorway in it. You may need to relocate your stove and range hood or you could have a range hood that you can see "in the round". You would lose those upper cupboards though. or 2. You could remove the other wall to the side of the doorway. This would then mean that your kitchen would open up to the living area but you would lose some full height cupboard space along that side. I also noticed that your TV is located in that corner. Do you need it there or can you relocate it to free up that wall? or 3. Perhaps you could flip your kitchen so that the breakfast bar is near the dining table rather than at the other end. The stove and range hood could then go at the end where the current breakfast bar is as well as upper storage cupboards. Having the kitchen open onto the dining area could be very nice if that's what you are after. It depends on the rest of the living area, too, whether you would like to open it up totally as well. There is a lot to play with here and it can be a lot of fun. I wish you the best of luck with your renovations.

How about a water feature? Inspiration.

Hi dolly 7, The shelving unit is constructed off the wall in front of the the cavity and sits on the floor. You would only need to fix it back to the wall so it doesn't come forward. It would not be good to suspend floating shelves on this wall unless it had a back panel going to the ground. See pic examples. Sliding doors were installed onto an archway first. Wall unit built in front of sliding doors as cabinet. For holding weighty items on adjustable shelves, try to keep the width of the shelves to a minimum i.e. 50cm wide x 18mm thick, otherwise they will bow. If you increase the width, you will need to put a shelf pin in the middle at the back. For floating shelves, back panel should go to the floor if wall has minimal structure.