The standard library is very unlikely to include, or at least expose, non-final standards. I personally plan to toy with implementing Kyber soon, and plan to produce an experimental age [0] plugin. If a TLS experiment were to gain traction, I don't exclude we might support it in the standard library, since it would be negotiated and we'd be free to drop it later on.

[0]: https://words.filippo.io/dispatches/post-quantum-age/