I'll tell you what I do...I have a credit card version of a Swiss Army knife, meaning it's got some of the more popular traditional Swiss Army knife components built into a little credit card shape, like this:
Photo courtesy of Amazon
On the right side, that's a little knife that slides out, and next to that, a pair of little scissors, obviously (the other stuff, just for FYI, is a little punch, a nail file/screwdriver, tweezers, a toothpick, and a little ballpoint pen).
It's about the thickness of three credit cards, so it fits pretty easily in a wallet. When I'm out and about, the scissors and the knife are very handy for opening those little packets you mentioned, as well as a lot of other things (clipping a hangnail, for example, or a stray thread).
At home, I do keep a pair of non-food scissors, for opening things like cereal boxes, snack chip bags, cookies, etc. As we get older, many of us get issues with arthritis or, like with me, tendon issues, that can make opening bags one of life's little frustrations.
If I were Grand Poobah Of Everything, I'd make it a law that all canned goods must have a pull-top, all bagged goods must be resealable, and all small appliances must have retractable/storable cords.
