I think it's more likely that they hacked these devices than that they have a way to blow up the batteries. Surely Israeli intelligence already knew what kind of devices they were using and modified a large number of them. Now to think that they are going to do this to any device including hardware wallets would be too paranoid. The best thing to do is to leave all electronic devices and go to the desert or Siberia far from civilization. Wallet providers have their quality mechanisms and usually they are the ones who sell their products, so I don't see any reason to be scared about it.