Tire plug kit. Did it several times when I was younger. They’re 💯 safe and will be effective. I don’t do it anymore only because the shop I get tires at offers lifetime patching for free. Yes–you need to do it or the air will slowly leak out giving you poor mileage, at worst a blown tire while you’re driving on the freeway.

I’d probably use a rope plug. I use extra glue with it and none have failed me yet. Most tire makers won’t approve of them tho.