I have night sights on all my defensive/carry guns and always will have.
In back and forth comments on the yes/no debate on night sights some people seem to assume that you will be in absolute darkness so will not be able to identify a threat. That is usually not the case in my own world. Interior areas can be absolute dark like the OP's dark interior stairwell, but...….
My wife and I walk three miles or more on most nights around the neighborhoods we have lived in. With security and landscaping lighting, moonlight and starlight I can easily see my night sights and my surroundings enough to recognize a threat. But, I still carry a small flashlight rated at 1000 lumens. I do not have a WML on my carry guns and never expect to have.
I much prefer combination tritium/fiber optic combination nights sights such as TFOs and similar. They are bright in low light as well as bright during the day. And I can see them with my flashlight turned on at night.
If you are facing a threat then that threat cannot see your night sights glowing. If the threat is behind you or to the side then they likely can see your glowing sights.
The only weapon mounted light I own is on my bedside handgun. There is now no one in my home except my wife and I plus we have small low wattage night lights plugged into outlets throughout the house so we can wander around without needing to turn on lights. If there is an intruder in our home I'm not worried about spotlighting them with my weapon mounted light.
For the OPs situation it seems to be an easy fix by using one or more of the many portable and battery operated motion activated small lights for sale at big box stores or over the internet. They can be adhesive stuck on walls or ceilings and will turn on whenever motion is detected. There are choices of light levels from bright to smaller. I use a couple on my basement steps.
My opinion only. Yours may vary and that's okay.