How would a bigfoot use its hands?
They aren't habitual tool users so it would be very different to us.
On what basis do you confidently assert that they are not habitual tool users?
Walking on two legs rather than 4 is a disadvantage in many ways. 4 legged animals are faster and more stable. That's why most large animals, whether predator or prey species, move on 4 legs. A creature would only evolve to walk on two legs if it made a substantial gain elsewhere to offset the disadvantage.
Why would an animal use only use 2 legs? Birds or bats do it to release their upper limbs for flight. Apes and monkeys are capable of walking on two legs and can use their hands for climbing, picking fruit, carrying things, grooming, etc. However, most of the time, they move on 4 legs.
Bears can stand on their back legs either to appear more threatening, or to reach things, or to observe something in the distance, but they habitually move on 4 legs.
Bigfoot, being heavily built and substantially over 6 feet tall is not optimised for climbing (or flight!) and they would only be expected to spend a small amount of time picking fruit, carrying things, or grooming each other, yet they are (nearly?) always reported as walking upright on 2 legs.
So why does Bigfoot walk on 2 legs? The most likely explanation would be habitual tool use.
Tool use is not restricted to humans. Simple tools are used by many creatures, and there are even several that carefully choose stones, and modify sticks, to use them as tools.
My conclusion would be that
if Bigfoot is a real flesh and blood bipedal mammal, then it is an habitual user of at least simple tools.