DAOs "governed" by a smart contract are only useful (and truly decentralized) for managing portfolios of native tokens/assets.

Most DAOs have a voting system and trades/transfers from the treasury execute automatically in accordance with the vote.

Any other class of proposal requires trust in someone to actually execute the voted upon plan. This is "The Principal Agent Problem" and it means governance isn't fully decentralized/trustless.

Since there are no other native assets to manage on Bitcoin, there isn't much use for a DAO on base layer. A treasury could just be a large multisig address and key holders could vote (by signing PSBTs) to make transfers from the treasury.

Nunchuck is a wallet that makes it easy to manage multisigs with multiple signatories.

Sidechains and layer 2 protocols that enable token issuance alongside a BTC token could choose to support a DAO-like contract.