Would there be a way to make a mod that's something like this? Is there one out there like that I never heard of? I assume there's probably a very specific type of script for this.

Highly secure area (players home or a safe city): A 1/100 chance of being attacked in your sleep, but only by sneakier creatures/characters. (Making sneaky creatures/character is actually easy).
Moderately secure area (a cutthroat type city): A 1/88 chance of being attacked in your sleep, again only by sneakier types.
Not very secure area (Such as somewhere where raiders live) : A 1/4 chance of being attacked in your sleep. Not necessarily by something or someone that sneaky.
Very insecure area (Sleeping basically in the wildneress): A 1/2 chance of being attacked in your sleep by most creatures in general, just about any non-unique npc or creature would be possible. Metaphorically speaking a bulldozer could ambush you with there being no real obstacles to prevent them.

I think if it worked it would be great making the game more challenging in a realistic way without making it incredibly frustrating. It would make using a bed a truly tactical decision, and there might really be a reason to want to use a bed in a realistically safer location. It would also for (some) people be exciting to have their secure bunker like home on occasion have infiltrators that attack. So how hard would it be creating such a mod? Would it be a really complicated process making it so only more sneaky creatures/npcs could ambush a player sleeping in more secure areas?

There were mods that did this for FO3.