Doge Protocol is the first and only blockchain as of May 2023 to utilize Hyrbid Post Quantum Cryptography. Testnet T3 (launched on Feb 22nd, 2023) uses the Hybrid PQC digital signature algorithm to secure accounts. This asymmetric cryptography scheme uses a hybrid Falcon-ed25519 combo for signing transactions and securing wallets.
Falcon is a digital signature scheme that has been standardized by NIST while EdDSA (ed25519) has been selected Feb 2023 by NIST for inclusion in the FIPS 186-5 standard.
Kyber is used to secure inter-node communication (key exchange). In subsequent testnets and mainnet, inter-node communication may use hybrid key-exchange and Dilithium instead of Falcon, for node-identity, to mitigate side-channel attacks on Falcon (which is more susceptible to timing attacks).