GNU Taler is a working implementation of "digital cash" in the spirit of Ecash. Since it doesn't come with its own currency, it cannot be used for gambling. It is quite telling that it has seen essentially zero adoption in the "crypto" scene.

Cashu is a working chaumian ecash protocol built on Bitcoin. It is quite functional and has some subset of bitcoiners actually using with, with many wallets and mints building on the protocol.