Ava Labs publishes Encrypted ERC, a token standard combining zk-SNARKs with partially homomorphic encryption and client-side proving, usable on the C-Chain and on custom L1s. It is a standard rather than a protocol feature, so nothing is confidential unless an issuer adopts it, and public deployments are thin. Permissioned Avalanche L1s offer opacity through restricted validator sets, which is a different thing from cryptographic privacy.
Private by design.
See how confidential transactions work on the networks you already use.