IIRC it just should look like normal TLS traffic. They are unique to each of the already public Tor relays not the users. What benefit would ECH bring? You can still look at the IP and know it's Tor.

All the "let's hide that it's Tor" work is done with pluggable transports [0] used in combination with unlisted relays (bridges). This way there can be multiple completely different protocols like obfs4 (looks completely random), Snowflake (uses WebRTC), meek (uses domain fronting) and WebTunnel (WebSockets over https) without a need to update the Tor spec and all relays.

[0]: https://spec.torproject.org/pt-spec/architecture-overview.ht...