“Any lawyers want to explain the legality of this”? That made me laugh.

Well, I’m not a lawyer, but the prosecution would destroy any motions to dismiss the case on the grounds of a fourth amendment violations. The firefighters had a duty to make sure nobody else was in that building that could be harmed. They could’ve just overlooked the fact there was enough fentanyl in that apartment to kill thousands of people - and not call police, but a firefighter is most likely not going to keep their mouths shut given they save lives daily. Kind of counterproductive.