My suggestion is to have the NPC’s that are in singleplayer, what I mean by this is having the animals roam around, like cats, dogs, rabbits, cows, fish, etc. Just like singleplayer, where there’s a cow crossing the road in the “texas area” and all that. Also, another thing about the NPC, having the planes as NPC’s flying, like in singleplayer, like the cropduster and the commercial aircraft, fighter jets, etc. Another last thing is how the NPC’s drive and act in singleplayer, they’re much more realistic and more interactive with you.
It is possible because when you “leave session” in a server, it has all those singleplayer NPC’s, now just have them in the server, that would be great