Ceiling should not be a bright flat white. It should have a drop or two of wall color added. Add some recessed small lights that can be directional toward the unwindowed walls. Adding light with a grey paint is not always the best solution.

You can add crown on cabinets if they aren't up against the ceiling. With high ceilings such as you have deeper crown & baseboard in white will brighten the areas up. Add as much white on the inside walls as you can. Bold art on the inside walls will also bring light in.

If you could get permission, adding a solatube to the dark side might help, without much cost. But, you know your board, so that might be an insane idea. If the entry door is on the "dark" side changing to a door with windows could help too, again assuming your board would allow it.

Covering your closets is a must for resale. I've seen these Ikea screens used, and that might make it pop: Kvartal rail and Grynet panel