Database built on blockchain? Queryable by SQL or nosql interface

Are there any completely decentralized, trustless databases built on blockchain? At a minimum this DB should be queryable through an SQL OR MongoDB type interface.

I'm assuming that there will be some performance and capability deficiencies at this point in blockchain tech maturity, but looking for something more useful than Arweave, IPFS etc... are on their own, particularly from a querying perspective.

Context: I'm thinking through how one might build a completely decentralized Web 3.0 application, using some of the familiar tools, interfaces and concepts of Web 2.0.