Your requirements keep getting larger on each answer. I think they are now:
- run command after all tests are done
- run a python cmd within RF
- run after logs have been created
So an RF run needs to produce the output.xml file to be able to produce reports from it. That file gets finished and closed after the last test. Once closed the 'report' and 'log' files can be created. So there is no way to run something in an RF run after the logs have been created.
I would use one of the ideas already given and create a wrapper script.
I currently do this in one run as RF/Selenium exhibits a catastrophic failure after running more than ~600 test cases within one RF run. (I do not yet know why) I split up the RF run into two runs based on tags and then run rebot --merge at the end to create one report/log