What do you mean by small drones in the first place?
First of all, I apologize for snapping at you. My thought in the original posting was to generate some discussion of innovative ways to combat superior armament. I was disappointed. Mostly, people discussed things that had been done long years ago, in a less technological age. Then there were the ones who dismissed everything summarily without offering much by way of discussion. A thermite grenade weighs 32 ounces. Relatively small quad-prop drones can lift 34 ounces, but other factors include the weight of an imaging system so the operator can guide the drone to its target and range. It doesn’t matter how much the drone can lift if it can carry the weight only 10 feet. So, I guess the final answer is that any drone capable of lifting the grenade and conveying it a target perhaps a quarter mile away would probably be too large to be viable as a delivery platform.