How do I enable a Google Workspace account to load an unpacked extension from C:?

[Peter Isakson]

One of my managed accounts does allow this - the Manage Extensions page shows buttons Load Unpacked, Pack Extension and Update; these work getting the manifest, background and content files from a local directory, and my extension works. It also works when I use an unmanaged @gmail.com account.

When I add a profile to Chrome using another managed account those buttons do NOT appear. I am a super-admin of the workspace but I can't find any setting that seems to control the ability to load an extension and from where (I don't need to use what seems to be avery complex process to get the extension approved for the store, even though it is Private).

What might be different for these accounts that can't load unpacked? I have used Gemini to do AI searches on the problem but it seems to return solutions based on obsolete versions of the admin console.

Thanks!