https://www.mintlayer.org/
a Bitcoin sidechain with its own governance and its own consensus algorithm called DSA, which mitigates the typical criticalities of the Proof Of Stake, through an anchoring system to the Bitcoin blockchain.
The goal is to bring tokenization and DeFi on the Bitcoin chain, including stablecoins.
In practice, it allows you to create tokens and exchange them with each other directly on the Mintlayer sidechain (also with Lightning Network), or exchange them in a completely decentralized way (DEX) with BTC, via cross-chain swap.
Another feature that I find interesting is the possibility of paying the transaction fees directly in tokens (as if on Ethereum, to understand, you could move USDC by paying the fees in USDC and not in ETH).
Security is closely linked to the Bitcoin chain: each block of Mintlayer is anchored to a block of Bitcoin, and there is a checkpointing system that each tot goes to write on the Bitcoin blockchain, to make the sidechain irreversible up to that point even in worst cases of attack by more than 50% of validators.
The MLT governance token will also be launched soon, with which it will be possible to participate in the governance of the sidechain through staking, and on 10 November the Testnet will be officially launched.
