That said, it's nice to see there's some serious work going into this new stuff... driven by a non-profit foundation https://radicle.foundation/ , that does make me take it more seriously, I will check it out.
Of course, any interactions with the blockchain directly (calling methods of deployed smart contracts, or transferring tokens), are decentralized, but if you want to verify the source code of the contract you're interacting with, the most convenient way again involves relying on a centralized service (etherscan or similar for other blockchains), while the decentralized way would involve downloading the contract source yourself, compiling it, and comparing that with what's on the blockchain.