Please don’t, it’s most likely going to end up in the trash because we don’t know what you’ve done to it, even if it’s sealed. How would you feel about a complete stranger giving you candy, food, etc?
I’m an airline pilot and was given a really nice chocolate bar by a passenger. I love the intention; however, I had to throw it away because I just didn’t want to risk it.
If you REALLY want to give crew a gift, go with gift cards or something like that. We always appreciate appreciative passengers!