Running a script shell as a system service (with hot key assign) in macOS Catalina

I am trying to run a script shell as a system service (with hot key assign) in macOS Catalina and keep getting [Errno 1] Operation not permitted. It is simply a line asking python (yes python 3) to run a file in a separate directory. If I copy-paste in the Terminal app, it works. If I run it in Automator, it works (they both have access to the whole disk in the security preference pane). I tried to give launchd full access to the disk (as for Terminal and Automator) to no avail. It was working perfectly up to macOS 10.14. Clearly something does not have the right permission but I cannot find what which process or deamon is responsible to system services.


Thank you for the help