I would clean and then just epoxy the concrete flooring. It will give it a nice shine that will help bounce light around. Keep the wall paint light and neutral, don't overthink it the new buyers will likely repaint.

Those steps look rough, that would be my main concern. I'd finish those for sure. That door also needs to be replaced with a full one. It's looking pretty beat right now and the half door look isn't great.

Thanks for the advice. A new door is a great idea. What about a glass one with grids to match the door to the study right next to the basement? Or do people not put those types of doors to basements?

I would just put in a regular door. A glass door isn't typically used for basements, plus it would be more expensive and if you're looking to sell go for the cheapest option.