osgVerse, a complete 3d engine solution based on OpenSceneGraph. It supports OpenGL/OpenGLES/Vulkan/DirectX/Metal backends, and also works on modern browsers using WASM.
osgEarth - 3D Mapping Engine & C++ SDK This is a modified version of osgEarth 2.10 to work with WebGL 2.0 (WASM) and osgVerse