Snacks and car seats, always a mess waiting to happen, so there are plenty of little containers designed to hold the snacks whilst providing easy access to little hands.
I got a double pack of Munchkin Snack Catchers. They range anywhere from around $4 to $8 for a pair depending on where you get them.
They look great, they are dish washer safe which is a huge plus and generally they get a great review.
The reality is, they're a bit shit.
The actual container is so flimsy even with the lid on that it can be squished quite easily, which results in all the snacks falling out. The opening in the lid is way to larger and flexible that anything slightly small for a snack falls out and the flaps don't hold anything back from falling out when little hands reach in to grab at stuff.
For all the good these things do, you really wouldn't notice any difference between using a normal open container but at least something like that you can put a lid on so they don't shake all the contents into your bag if your carrying it around which this will do as it squishes together.
Find something else would be my advice.