What are the solutions on Windows to split the OpenGL rendering from the display?
By that I mean that a process in the background takes care of the whole scene drawing, and a separate process should simply render a texture with the result.
Most likely browsers have some solution today to handle rendering in various sub-processes.
On Linux, we can use EGL_MESA_IMAGE_DMA_BUF_EXPORT, as demonstrated in https://blaztinn.gitlab.io/post/dmabuf-texture-sharing/