There's a fun short story called 'The Road Not Taken' from the perspective of an alien civilization that stumbled upon agrav tech but is otherwise at a Napoleon

There's a fun short story called 'The Road Not Taken' from the perspective of an alien civilization that stumbled upon agrav tech but is otherwise at a Napoleonic technology level attempting to evade earth. From their perspective a civilization not stumbling upon agrav early on is preposterous. Personally assuming the objects are actually some kind of non earth craft autonomous drones make the most sense to explain their behavior, particular their seeming interest in nuclear facilities.