I think you are referring to the SignedAmount type in bitcoin-rust: https://github.com/rust-bitcoin/rust-bitcoin/blob/master/units/src/amount/signed.rs#L84

cdk defines it's own amount type: https://github.com/cashubtc/cdk/blob/main/crates/cashu/src/amount.rs#L32

This `Amount` is independent of the `CurrencyUnit` type so you can use it for bitcoin, stablecoins, beefbux or whatever. I'm using it to track difficulty of mining shares.