Chacha20 can sue 192-bit nonces with a 256-bit key. A single function returns the key, the authentication key and the nonce.

The name changes in order to avoid arguing why ChaCha12 is as secure as ChaCha20, because the implementation is compatible with it.

The final specification https://kerkour.com/chacha20-blake3 and the research used https://kerkour.com/chacha20-blake3 can be helpful.