Is it possible to use what we know about Earth to find out more about the Earth’s Moon? At least we can extrapolate the proportions of Earth’s layers and see whether that fits for the Moon. It looks like this:
This is a guess, but it fits very well, and is in coherence with the convection cell theory.
What is new in this is claiming that the inner core has the radius of about 123 km. The other layers have been measured according to Apollo seismic data.
Extrapolating in this simple way is of course a bold method, but what we begin with is this picture of the Earth:
As long as direct measurements are not violated, this can be seen as a valid contribution to the discussion. As far as I know the diameter of the Moon has not been measured directly yet.