how can i use a bytebuddy method to get the public instance in an object received as an argument to the return value of a methodcall?

This is not possible as of Byte Buddy 1.10.18, the mechanism was originally created to support getters/setters when defining beans, for example. That said, it would not be difficult to add; I think it would even be easiest to allow any custom byte code to be dispatched as a consumer of the method call.

I will look into how this can be done, but as a new feature, this will take some time before I find the empty space to do so. The change is tracked on GitHub.