Diffraction limits are most visible for small apertures (high f-numbers). For surveillance cameras, I would expect* sensor size to be the bigger issue, because

Diffraction limits are most visible for small apertures (high f-numbers). For surveillance cameras, I would expect* sensor size to be the bigger issue, because as long as sensor size is fixed, signal to noise will be limited by photon noise (the noise created by the randomness of photons themselves), no matter how good the sensor is. Realistically, if this is a goal, then manufacturers will just increase the sensor size until the goal is met. This isn't a cell phone, so the sensor size constraints are pretty forgiving for this platform. * Note: I am no optics expect, this is just what I've picked up on my own.