Tim didn't mention a contemporary sibling tech at AWS which should not be thrown out with the bathwater: private (centralized), immutable, signed ledgers. Their version is called QLDB and does have concrete applications where you need an provable audit trail of a stream of transactions with search and index on top. I was on a team at a fintech closely engaged with AWS to prototype a money movement system using that as a central ledger. There's an open source one with similar properties on GH somewhere, also.

It's not sexy like blockchain so it seems marketing had to slip in some Quantum to bump the buzzword sex count.

If financial industry regulators were serious about catching laundering or book cooking, they would demand this kind of tech as a foundation of compliance reporting.

Do you have any other clues for finding that open source project?

It sounds very interesting to me.