I've usually checked stuff in my baggage. I simply cannot see going places without a knife, and if I am checking the knife, it's not too much to check other things.

However, I also have carried on a bunch of flights in the last year a P-51 can opener and about a dozen feet of paracord, both on my keychain, and they never get a look. I think adding a firesteel and/or a whistle would also get no attention. If I wanted to hike, I might add in a couple of strong garbage bags and a couple ziplocs, as well as water and snacks, and that would give me a little kit.