What about a complex system involving a sidechain for Bitcoin that uses Zero-Knowledge Proofs (specifically Succinct Non-Interactive Arguments, SNARGs) to manage the pegging & unpegging of Bitcoin to/from the sidechain?? (A system that can enhanced privacy, efficiency through low communication proofs & a mechanism for secure two-way value transfer between the main & the sidechain).

Private Key Wrapped in ZK BBox',

'Pegging & Minting S-BTC', Why? Users send BTC to an address on the main chain & submit a proof to the sidechain. Once validated, S-BTC is minted on the sidechain, effectively representing the pegged BTC. This allows for value transfer between the main chain & the sidechain.

Proof of Burn & Key Reveal, Aggregate Withdrawals & Ordinary Users, Low Communication SNARGs.

Challenges with Drivechains in terms of fees to market cap ratio: the potential limitations of sidechains (like drivechains) when the fees required to operate on the sidechain are high compared to the market capitalization of the sidechain. Important to ensure the viability & sustainability of the sidechain..