Sounds like misinformation. Particularly in politically-aligned flamewar sites like X, you'll hear both sides inflate their actual capabilities beyond what is logically possible. All you need is a video of a blurry explosion to get 90% of your viewers to believe you.
To the point - you just can't get a lithium ion battery to discharge in an explosion, otherwise they wouldn't be allowed on airplanes at all. The most dangerous state a battery can reach is called thermal runaway, where one or more cells begins a self-heating cycle until it is fully discharged. This is a laptop battery, likely between 50-100wHr in capacity and therefore tens or even hundreds of times larger than what goes in a pager or radio: https://youtu.be/oieH2wwDGzo
Inducing such a state remotely would require you to physically damage the device. You cannot do it by overheating because there are hardware-enforced and firmware-enforced thermal fail states that will shut off the CPU or battery before causing damage (aka junction temp). If you did manage to, somehow, override these limits and intended to overheat the device into such a state of runaway, the owners would feel the device become physically hot and even watch it inflate before it becomes dangerous as a fragmentation weapon. This attack could only feasibly be executed by using an implanted explosive. There is no possibility that this is a generic exploit, even with the most charitable interpretation of Mossad capabilities.