Hi Fskyline,
At the moment there is no definite date on when we will be fully supporting HTML5/WebGL. We’re currently waiting on an update from Emscripten which is used in conjunction with UE4 to to get games working on the HTMl5/WebGL platform. Once that’s out, more support for the platform will follow. In the meantime, it is possible to go ahead and start working with HTML5. You can find documentation here: Sharing and Releasing Projects for Unreal Engine | Unreal Engine 5.1 Documentation
Hope that helps!
-Max B.