This is the 13179th most frequent Russian word.
микродроны
"Microdrones" – small, unmanned aerial vehicles.
Here, 'микродроны' is used as the direct object of the verb 'представили', indicating what was introduced.
Разработчики представили новую серию микродронов.
Developers introduced a new series of microdrones.
In this sentence, 'микродроны' is the subject of the verb 'могут использоваться', referring to devices capable of observation.
Микродроны могут использоваться для наблюдения.
Microdrones can be used for observation.
'микродронов' functions as the object noun in the genitive plural form, specifying what was tested in diverse conditions.