I would remove it and add a small painting.

What she said ^^^
Shelf doesn’t look right there.

Yes, remove the shelf and place a bold and colorful piece of art that you love.

If you can afford it id put one floating walnut or similar wood shelf very close to backsplash edge. A wood tone will tie the kitchen floor w the cooler other surfaces and you will get use out of a shelf there, I wouldn't miss this little spot for an opportunity / details count.

I would rethink adding an upper cabinet there because it will create symmetry around your window (which is ideal) and provide needed storage. Just open the blinds and look out the window when you’re doing dishes lol. You have a dishwasher so I don’t think you spend too much time there anyways. :)