Based on the flight times and 100 mile flights ~100 miles off the coast and the investigated boats in the area...they couldn't be small. At least not with current consumer battery technology. Maybe if they were launched by a sub?
There's a youtuber that has a multi-hour autonomous drone, but it's solar powered and this was at night.
There's a youtuber that has a multi-hour autonomous drone, but it's solar powered and this was at night.