Upgrades for Bitcoin need to get consensus from miners on the network. The last vote for Taproot to lock in is an example:
https://taproot.watch/Miners have to signal their support and help to lock in Taproot. It is a decentralized consensus but satoshi does not call it as DAO.
To my understanding, no BTC is not a Decentralized Autonomous Organization (DAO) because the network is maintained by miners from around the world and it's the consensus among codes on their computers that leads to building a new block on the blockchain.
Because these sets of minders are not sitting under one umbrella group/organization the running and maintenance of BTC is fully decentralized without an appointing group taking charge of mining events etc, and thank God for that!!!