I still think it's a slippery slope to include such specialized APIs that most people don't know what to make of.  This reminds me of `RAND_egd()`.

If ChaCha20-Poly1305 is always /at least/ as secure as AES-GCM (and sometimes more), then we should simply prioritize it in the cipher list, regardless of a potentially poorer performance that probably never has an actual impact on the Python-written application (correct me if I'm wrong here).