The integration of (“permissionless”/integrates “natively”/doesn’t require support from the main chain.)!
https://forum.dfinity.org/t/direct-integration-with-bitcoin
https://forum.dfinity.org/t/ckbtc-a-canister-issued-bitcoin-twin-token-on-the-ic-1-1-backed-by-btc
https://forum.dfinity.org/t/long-term-r-d-integration-with-the-ethereum-network
https://forum.dfinity.org/t/cketh-a-canister-issued-ether-twin-token-on-the-ic
…