I meant something more like encrypted SNI in TLS 1.3[1], but that has covering as an explicit design goal, so I guess that answers my question.

Still, it's a matter of politics, and not of technology. Google here chooses to stop covering for Telegram/Signal, even if the technology allows it.

[1]: https://www.ietf.org/proceedings/94/slides/slides-94-tls-8.p...