Is there any mods that add roaming NPC groups like bandits or something to the game. 

Can you please elaborate. Do you mean like bots that just walk around to practice aim? or do you mean bots genuinely roam with guns?

Merged post

This might be like what your looking for:
https://umod.org/plugins/human-npc

Bots that roam around with guns. Not just static AI. Really far stretch but I just wish Rust had better AI

On this site there is only  https://umod.org/plugins/human-npc

Dovic add me as a friend on discord Razor14150#7265 and Ill square you away