If you haven’t already, search ’wainscoting narrow hallway’ for lots of pictures. It might give you ideas.

What style is your home/decor? Can you show the main adjoining room(s)? Not bedrooms, but living or dining or whatever.

Wainscoting or not, art and a rug or rugs would look nice. And I’d consider getting rid of the attic door cord pull and have a ring/hook instead.

I would not add wainscotting to your space.

I personally would paint the corridor a lighter hue, replace the light fixture and add a runner.

I would start with much better lighting . What is the width of that hall? IMO trim will add to the already narrow space . How long is the hall? A bit more info gets more help.

Improve the lighting, find a nice semi-flush or pendant, paint a light colour.

I like Jilly's pics...I found some more that illustrate how good it could look

before:

during:

after: