How do I export Godot scene for web HTML?
I use Godot Engine v3.0.6. I have downloaded appropriate template and successfully exported scene, but when i try to browse it I receive error: WebGL 2 not available. How do i fix this? Is it possible to export scene with earlier version of WebGL, so it can run on most browsers and devices?
No, WebGL 2 is simply a requirement of the code the Godot Engine HTML5 export generates, as stated right at the start of the documentation. This is not something you can "fix".
Personally, I feel it's a bit early to use this technology for any mainstream projects, but that's very much a matter of opinion. As an alternative, Unity offers a similar WebAssembly-based pipeline, which has matured a bit more and offers WebGL. Or you could use actual web-based technology to develop for the web in stead of cross-compiling, which might or might not make sense given your project requirements.