Not a proficient app developer so feel free to edit the title to match the terminology.
I want to understand what part of these new python modules communicate with what part of the old stuff. You mention a REST API is involved, RhinoCommon is involved. Rhino Application and Zoo licensing is involved. Pythonnet module is involved. Rhino 7 is involved when using RhinoInside, Rhino3dm module, compute.Rhino3dm, etc.
How does it all work, what is the idea behind all of this?
Currently it all seems a bit scattered. Unclear.