Difficulty – What is the lowest possible value for your goal?

A similar question has been asked here, but the answer doesn’t really provide an answer.

This answer states that the lowest possible value for the goal is “all 0 plus 1“. Peter Wille In the comments, they denied this and wrote that the goal could be zero.

But considering how the target is encoded, could it be 0? nBits? The smallest legal value for the lower 24 bits is 0x008000, and given that the minimum exponent is 3, it appears that the lowest possible value for the target is 0x008000. nBits 0x03008000.

So what is the lowest possible target value for nBits?