I've installed python 3.9.5 using the universal2 installer on my M1 MacBook.

Debugging this python using lldb doesn't work because the debugger cannot attach to the (newly launched) binary.  This appears to be due to a missing entitlement in the signed executable.

Background: https://developer.apple.com/forums/thread/676028?answerId=666834022#666834022 (in particular the first reply).

There's a reason for that. What the discussion in that link fails to note is that elsewhere Apple warns that that entitlement is understandably prohibited in distributions submitted to the Apple notarization service. See the "Avoid the Get-Task-Allow Entitlement" section here: https://developer.apple.com/documentation/security/notarizing_macos_software_before_distribution/resolving_common_notarization_issues. I haven't verified that that is still the case but I'd be surprised if it weren't.

I think one solution (and possibly the best) might be to manually re-codesign the installed binaries if you need to use lldb with the python.org binaries. If someone comes up with something that works, we could document it somewhere with appropriate warnings about security risks and advice to reinstall when finished.

Should we add documentation about this? 

The truly annoying bit about that discussion is that its probably easier to just install gdb and use that to debug extensions.