-a credit card with little to no debt on it.
I heard about a guy who had his business cards made out of some useful, edge holding stainless alloy, that and a few credit card sized sheets of wet/dry sand paper would give you the ability to make a sharp blade that was re sharpenable many, many times.
If it's TSA approved, it's probably not that useful.
See about the max size of scissors and pliers that are allowed, those plus a beefy flat head screwdriver that's TSA approved would give you some basic functionality.
Final thoughts, not useful to the OP;
a pair of Knipex pliers and a reliable knife are better than most any multi tool...
Except that if the multi tool didn't try to compete with the pliers or the knife, then that would probably be a pretty good multi tool.... swiss army knives are pretty nice. I like the one that has the wire puller, and the awl, and the saw, and a flat ground, razor sharp knife blade, and the scissors. Not sure they actually make that one, they usually only give a few of those in slim configurations.
Once they get too thick their utility starts suffering from their bulk.
I don't use the term TSA-approved, I use "TSA-friendly". There is a pretty large grey area. Is it pointy, is it grippy (a grippy pen is a tactical pen which may or may not be allowed), is it a pointy tool (6" calipers).
There is a little leatherman (Style PS, ~$30) with no knife blade, but with a little pair of scissors. It has a little clip on it - heavily recommended to clip it to the outside of the bag and then it can be quickly seen. I've lost mine though, not sure where (yeah probably when it was clipped to the outside of my bag).