yes, to run Python code on any PC you need to have Python and any dependencies installed - even when running it via PyXLL. You could set the python path to somewhere on a network drive and have your code deployed there, if that helps.
You can write values into Excel using win32com, either from a second thread in Excel using PyXLL or from a second process running on the same PC outside of Excel. The automation examples included with PyXLL show how to write values back to Excel. Another possible option would be to use an Excel RTD function (real time data). The pywin32 package includes an example of how to do that, and if you search this forum for 'RTD' you will find a post with an example of how to write a PyXLL function to get results from an RTD COM object.