Cashu is a cool project but is not going with the federated model. You get improved privacy over a traditional lightning custodian such as Wallet of Satoshi but you have the same custodial risk.

With fedimint the custodial risk is minimized since it is a multi sig custodian. 

 Wallets with multiple mints? 

 Use my wallet < use my wallet and i cant see what you do < use my wallet and i cant see what you do and i have to collude rug you 

 Have you formulated much of an opinion on validity rollups? https://bitcoinrollups.org/