Expected to use the importlab command-line tool on Windows but:
'importlab' is not recognized as an internal or external command,
operable program or batch file.
I saw importlab was in fact sitting in C:\Users...\AppData\Local\Programs\Python\Python38-32\Scripts, but I guess it wouldn't do anything without an extension, so I just renamed it to runimportlab.py to avoid circular reference and works fine.
runimportlab.py --tree script.py