Thanks for in-depth review! That's really nice to read :)
About the WebGL issue on macOS Chrome, that's surprising as the game should use WebGL 1.0 (GLES2 in Godot) which should be supported by WebKit. Do you get the same issue if you export your own Godot-made game to HTML5? (You should be able to test locally by configuring the HTML5 export preset and use the one-click deploy option that should appear in the top-right corner. Note that if your game uses GLES3, that's WebGL 2.0 which is not (yet) supported by WebKit.)