Nothing in an electronic device, save for a very overvolted capacitor, could come anywhere near to as explosive as these were. Even LiPo batteries don’t explode like that.
These were explosives planted in the devices when being manufactured.
Not sure if you’ve seen videos of the explosions or the aftermath.
Sweden is in general a no-fun zone. Gotta have a license to have fun.
Also the school system teaches kids to be good little drones.