How small could drones get?..........I just tried to swat a clothes moth and missed......

[Yorkshire_Pud]

but watching it in the turbulence the thought "how small their brain is but yet they have abilities our drones are only beginning to get near, I wonder how small the 'thinking chips' inside a drone can go?" occurred.

 

[MAvic_South_Oz]

They are on youtube with cameras and all, about 1-1/2" square.
Controller even holds the drone !

I think the video I saw dates from 2016, so who knows what's out there now.
Just checked, they are out there still US$40.

Of course drones are smaller in many fields, look at nano drones in medicine.