Is it possible to be able to play my ACOUSTIC cello while standing/walking without using the spike?

Yes but with a lot of difficulty. I've heard of (but never seen or done) people rigging up a kind of harness to keep the cello attached to their chest and at the right angle. I doubt it's all that effective and you wouldn't be able to make a full sound, but yes can be done. You don't want to wedge the peg behind your ear for partly obvious reasons and also the stress you would place on your neck, You also can't play properly whiole holding it up with your LH. Some sort of harness that also makes sure the cello stays out at a manageable angle is the only solution I can think of, but even that is going to give you sore shoulders/back.