You are limited because of security restrictions on your ability to carry lighters and sharp instruments. I have found that it's still OK to carry small firesteels and tinder in a small waterproof container on flights, as well as a striker as long as the the striker is not sharpened to a point.
I also carry a pair of nitrile gloves, a foldable N95 respirator, a small container of painkillers, a small button flashlight, a small bottle of hand sanitizer, and a very small headlamp (Petzl e+Lite) in my briefcase while travelling.