What is Pi Coin & how does it work?

Could you please elaborate on the concept of Pi Coin and its operational mechanism? I'm particularly interested in understanding its uniqueness and how it functions within the cryptocurrency landscape. How does Pi Coin differ from other digital currencies? What are the key factors that drive its value? Also, how does the mining process for Pi Coin work? Is it similar to traditional Proof-of-Work or Proof-of-Stake models, or does it employ a novel approach? Lastly, what are the potential risks and challenges associated with investing in Pi Coin? I would appreciate a comprehensive yet concise explanation of this intriguing digital asset.