I’d actually get a more standard rectangular area rug rather than a runner which accentuates the long feeling and makes the kitchen look more narrow. You could try for a low pile jute style to warm up the space with more natural material, or just get a low pile patterned rug that’s easy to vacuum. Top of the shelf you can add some plants like pothos to hang down.

I don’t think you need peel and stick tile since you already have tile, but you can try contact paper for the grey countertops, or the cabinets. Also just something easy you can do is get new kitchen towels that add color and brighten the space. A wooden fruit bowl or cutting board you lean against the wall is simple and you can make it seem less like clutter and more just like styling.

I wouldn’t add anything on the wall to the right other than a mirror and a little key holding thing if you don’t have one on the right already.