Two things to bear in mind when it comes to administering Narcan intra-nasally (up the nose): you cannot titrate the dose, and it can kick in pretty quick, depending on the patient. We were shown a training video which featured bodycam footage on the mainland of cops and fire responding to an OD on a bus. Narcan was administered, guy woke up agitated, refused to be searched and questioned, and eventually pulled a gun and fired wildly. One firefighter was struck & killed.
Point is this: Narcan given by IV can be given in small amounts at a time, and we can wake the patient up just enough so they'll breathe on their own. With intra-nasal Narcan, they're getting everything at once. When they wake up, they might not be expecting you to be hovering over them, and may not react well to it. If you want to carry Narcan and administer it on your own, that's up to you, and our Good Samaritan law should cover you-- just be careful. Also, it's not just druggies and bums OD'ing-- keep in mind there are kupuna out there with dementia who may have accidentally taken too much of their pain medication. Not everyone is fortunate enough to have a caretaker managing their meds.