Well, there's always Unreal, Godot, and Unity. Ambient is something very different and takes advantage of WebGPU and WebASM to deliver a networked 3D gaming experience in the browser. IMO this is a fantastic example of what our whole internet is only just now capable of in a nice little package. Sure both Unreal and Unity will export to web, but there's a whole lot in between loading one of those up and shipping it.
You should try out the Ambient quickstart. You won't regret it.
One of the other important things is not too out-shadow people's own creativity.
If you start with high-content flashy demos that paint a certain picture, people aren't going to activate their own thinking-muscles & dream up their own uses. Having lo-fi roughed out assets is less intimidating and more open ended for the target audience.
Ambient does a much better job imo targeting people who would use it & be excited, by turning off & turning away the those who just want to be razzle dazzled by flashy demoes. That shit is actively harmful to have as your audience.
You should try out the Ambient quickstart. You won't regret it.