Allow Accessing Render Buffer while Rendering in bpy

When rendering (in my case, single image with Cycles) in background mode with bpy , I would like to access the render buffer while path tracing is converging (i.e., what the user sees when they render in the blender app).

The bpy.app.handlers.render_post and bpy.app.handlers.render_write only fire after the frame is rendered, and there doesn't seem to be any way to access the render buffer without modding and compiling from source.

The use case for this is streaming a render to a remote user (e.g. browser tab) while rendering .