Pandas grip bamboo with an opposable thumb, just like a human or a monkey, which is why they can sit there holding a stalk and munching away so dexterously. A bear with a thumb, basically a person in a panda suit.
A panda's 'thumb' is not a thumb at all. Like all bears, the giant panda has five regular toes on each front paw, none of them opposable. What grips the bamboo is a sixth, thumb-like nub on the wrist, an enlarged version of a small wrist bone called the radial sesamoid, which evolution stretched and repurposed into a crude opposable pad. It works as a thumb-substitute for clamping a stalk, but it has no joints to bend like a real digit and is anatomically a bone from the wrist, not a finger. Stephen Jay Gould wrote a famous essay about it as a showcase of how evolution jury-rigs clumsy solutions from whatever is lying around, rather than designing clean ones. So the panda did not evolve our thumb. It grew a knobbly wrist bone and made do, which is far weirder and more interesting than a borrowed human hand.