@jkoen Your shortcut can run a PyThonista script and pass an argument via url scheme

Url = pythonista://MyScript?action=run&args=argument
Open url

Your script can recall your shortcut via url scheme

webbrowser.open("shortcuts://run-shortcut?name=[name]&input=[input]&text=[text]")

See https://support.apple.com/en-en/guide/shortcuts/apd624386f42/ios