The documentation for CF_HDROP says
The data consists of an STGMEDIUM structure that contains a global memory object. The structure's hGlobal member points to a DROPFILES structure as its hGlobal member.
win32clipboard.GetClipboardData has built-in support for CF_HDROP. It decodes the STGMEDIUM and DROPFILES structures to produce a tuple of file names.
The documentation does not state that SetClipboardData has the corresponding code to construct the STGMEDIUM and DROPFILES structures from a tuple of file names.
I don't know enough about Python or its FFI to know how straightforward it is to construct the structures and pass them to the SetClipboardData function. Or if there is an existing library that will do this for you.