There is a weapon mod+cyberware which changes your weapon to non leathal its a damage mod with the added non lethal. Cant remeber what cyberware it was whether it was optics or smartlink (hand).
The rocket launcher cyberware has a tranq round will one shot anyone...even bosses its broken af.
Any gun that uses electricity as its dmg type is non lethal. There is a nasty smart smg which procs electric explosions, only place i know you can defo get it is a nice Araska mansion in north oak, i think. Its inside the building 6 guards...GL.