You would have to guarantee those phones would eventually end up in the right person’s hands.
Otherwise if you sabotage 100 phones and only 30 go to your targets, even if you only detonate those 30 there are now 70 phones out there randomly floating around with enough explosives to kill some random person.
For smartphones they actually could, they could tie the lipo pack serial number to the imei and work everything out from there.
Then make sure it’s been unlocked via biometrics within a second or so.
It’s very rare that someone else holds a phone to be unlocked for you, though it does happen, still the closest to a targeted kill.
You would have to guarantee those phones would eventually end up in the right person’s hands.
Otherwise if you sabotage 100 phones and only 30 go to your targets, even if you only detonate those 30 there are now 70 phones out there randomly floating around with enough explosives to kill some random person.