For Pickable items, use Area / Area3d and then connect an on_area_entered() or on_body_entered signal() depending on what type you are using. If you are using a kinematicBody or RigidBody for your player, use on_body_entered(). Add your player to a group "player" and then check in the on_body_entered() function in the script if the colliding body is_in_group "player". Then write the script to trigger the animation if true.