These appear to be actual explosions, not battery combustion (there's footage on Twitter of at least one of them going off, it's a detonation rather than intense burning)

Definitely some non-standard internals in those devices...

Can you share a link to the Twitter post? If it's graphic, please mention so.

One (graphic) example: https://twitter.com/GlobalWObserver/status/18360589108615294...

Surely just supply chain infiltration and regular explosives no?

Agreed, the story mentions that the exploded models were all the latest ones purchased in recent months

Wouldn't this be too easy to detect -- for example tripping airport security (or other X-ray security systems, govt. buildings etc).

Well if you have personnel who regularly carry weapons and/or explosives maybe those checks don't apply...but anyway this is mere speculation.

I think a state actor would be able to make an explosive look like a battery on x-ray.