Yep. Built with Bevy similar to how Godot is self-hosted. They are still figuring out the details like which UI framework to use and how to save scenes. Which abstractions to introduce - nodes like Godot, objects+components like unity, etc? Then debate on how "prefabs" are designed - are they just bundles? Entity and component serialization.... Tons of architectual decisions.
It's coming together.
The UI framework will be bevy_ui just like godot uses godot ui library. What needs to be done is improve it so it can actually work for making a complex app.
Oh and if you care about "deep level details" then i can still say fyrox has better internals. I know people who have given bevy many more chances than me and each time ran into a brick wall when writing an actual game.
It's completely expected that it doesn't click for everyone, but I don't get why you are framing it as if hitting a brick wall is the only experience that people have when making games with bevy. Plenty of people just don't like the ECS model. That doesn't mean that bevy is bad. It's just not for them. We are lucky enough that there's a great alternative in the rust gamedev ecosystem like Fyrox for those people. It doesn't have to be a competition.