[Answered ]-Module not found error in Python script running as a Windows Service

After a few more tests (read: shots in the dark) and doing some more extensive digging in Google with the resulting errors, I found this article on Github.

The poster’s issue was very similar, just with a different specific error. Owing to circumstances, the poster was able to pin it down to an incompatibility between pywin32 and Python 3.11 (since the issue started only when they upgraded from 3.10 to 3.11). The clincher was that the issue went away when they reverted to 3.10. (UPDATE, 2023-10-19: Issue is also triggered when using Python 3.12.)

So I rebuilt my environment with the current 3.10 release (3.10.11), installed and ran the service — and now it works.