I usually carry a lighter (I don’t smoke) and a small lens. Even with an empty lighter you can rotate the sparker slowly and drop the dust onto toilet paper, then give it a good spark - you’ll usually get a flame...then have kindling ready. Of course the lens is only good with sunlight but it’s small enough for a wallet.
They’re just handy things to have on you...never know when they might be useful - like a small pocket knife.
One of the most reliable ways to distinguish humans from baboons is that a human always carries a knife and a way to make fire.
I used to always have a small pocket knife on me until TSA kept taking them from me, so I’ve grown out of that habit. I should start up again though, it’s a handy tool, and I don’t fly as often as I once did. (Except this year I’ve flown more again. Lots of family events this year. I dislike flying, but I’m not afraid of it.)
Yeah, a small lens works and it is very light and compact. As long as the sun shines, you are good to go. It is great for a secondary fire starter. Another good one is steel wool and a nine volt battery. Very light weight and compact. Works in any weather conditions.