I think the Accessory Slot would provide a nice opportunity to equip an utility item. Lots of people are complaining about the lack of weapon lights on their weapons, so why not allow them to equip a light source into the accessory slot?
You could also do some new conditions like “Noxious Gas” and give an Airpurifier unit that creates a small area of breathable air.
People could start into the game with an Ammo box or a Med kit.
There are, of course, other fun things one could do. Maybe an accessory slot that allows you to carry a gun servitor skull, providing a limited area denial around the player. I think there is a lot of utility that could be used here.