I see that in the blog post regarding Element Call, they say that Element Call is fully implemented using Matrix:

What’s more, Element Call is built entirely on Matrix: it doesn’t need any additional servers to get going. You can run it against your existing Matrix homeserver to provide complete self-sovereignty… while still being able to talk to anyone else anywhere on the wider Matrix network!

Does this mean that group voice, and video calls will work on other Matrix clients? Element seems to have the ability to create something called a "Video Room" which seems to match what discord does with the pop-in/pop-out voice-chat room; however, if I look at that room in another client like Nheko, it does not appear to have the functionality. Is that simply because they have yet to implement it themselves, or is it that the feature is unique to element, and, as a result, will not work with any other client? If so, is Matrix going to implement it so that it can be mirrored across other clients?