HD, you probably don't need a sling. I have opinions, but really you aren't going great distances, aren't manhandling people etc.
If it came with sights: good. Not missing is good. If it didn't: dance with the one you brung or go buy another gun. Not worth the hassle-cost of upgrading.
You NEED a light. Don't shoot the neighbor or family. Lots of options, this is a reasonable cost, performance, ease of use:
https://www.amazon.com/Streamlight-69600-TL-Racker-Lithium-Batteries/dp/B07P9RSS32
Get this (or similar):
https://sjhardware.us/product/type-1-follower-and-magazine-spring-package/
Safe, more reliable, etc. Bright is nice, but mostly it's plastic and has a different shape. Nub in the middle confirms it's the follower, not a shell. Plastic slides smoother, and factory Mossy springs aren't super strong, all replacements are better.
Put velcro on the side of the receiver. Buy these:
https://skdtac.com/esstac-shotgun-card/
Or similar. Chinese knockoffs abound on Amazon, eBay, etc. Velcro makes them easy to replace when they wear out, AND you can have a few spares in the place the shotgun lives, slap new ones on to "reload" the gun.
Learn how to run it. Practice. Learn how to unload without running shells through the action (you can!), etc.
Buy some dummies. If you can't get to the range enough for shooting, at least very triple check unload it, then practice unloading, loading, etc. Even if you have a range, unlikely to let you shoot at night so (carefully, very empty, no one at home) move through the house at night using the ambient light and the forearm light only, at least once a year to get used to how it works, what you can see, what you cannot.
Get a flashlight. Keep with the gun and ammo. Put in your pocket so you can light up stuff without pointing a gun at it. Worried about no pockets? Get a neck-size lanyard or make it a headlamp.
Lock it up. Do no not hide it. Forget kids, thieves know all the tricks for hiding. Find a way to secure it for quick access. I like pushbutton mechanicals. I like this:
https://www.amazon.com/V-Line-Quick-Access-Keyless-Shotgun/dp/B000T24OGA