The good news with this is that we've built our implementation on top of LiveKit, and you can look at the source, so you can see the E2EE in the browser. The encryption key for video/audio is only known to the client, so it's only known to whomever you share it with (the other participants). You can also look at your browser's WebRTC internals to see who it's talking with. Eventually our plan is to support TEE-based attestation of the Multi-Party Relay hops as well.