If an effect refers to a Food, it means any Food artifact, not just a Food artifact token. For example, you can sacrifice Tough Cookie (an Artifact Creature — Food Golem) to activate Maraleaf Rider's ability (an ability with "Sacrifice a Food" in its cost).

Food is an artifact type. Even though it appears on some creatures, it's never a creature type.

You can't sacrifice a Food to pay multiple costs. For example, you can't sacrifice a Food token to activate its own ability and also to activate Maraleaf Rider's ability.

Whatever you do, don't eat the delicious cards.

If the target creature is an illegal target by the time Pippin's Bravery tries to resolve, Pippin's Bravery is removed from the stack. You won't be able to sacrifice a Food to it.

If an effect refers to a Food, it means any Food artifact, not just a Food artifact token. For example, you can sacrifice Lembas to Pippin's Bravery.

You choose a target creature as you cast Pippin's Bravery, but you don't choose whether to sacrifice a Food until the spell resolves.