Are off-screen NPC needs in The Sims 4 generated in real time or are the changes randomized?

How do Needs variations in The Sims 4 apply to off-screen NPCs (e.g. non-family Sims that the player does not actively control)? Are the changes determined in real time based on the environment the NPCs find themselves in and the objects they can interact with, or does it stop tracking them through the game world and adjust values "behind the scenes" to create the illusion of activity?

It seems like the former would be expensive on computing time, but I can't find any conclusive evidence for either option online. My initial guess was a variation of the job Rabbit Hole applying to off-screen Sims, but it'd be interesting to know how this is handled from a technical perspective.

Off-screen lots are not loaded -- the game literally does not know what is around them, so it cannot simulate them interacting with "nearby" objects.

I believe it's possible to put, say, a Piano in an un-pathable area (behind a door a particular Sim is forbidden from entering, for example), but when you're off-lot, that Sim will have "Improve Piano" available -- because the game only checks that there's a piano on the lot, not whether it should be possible to make use of it.

This is different from The Sims 3, where both lots were loaded, and the Sims could actually make use of nearby objects.