I worked with the Pyinstaller folks to get my problem addressed. The thread can be found at https://github.com/pyinstaller/pyinstaller/issues/6293 for any Pyinstaller who stumbles upon this. (Or just delete if you wish.)

This is extremely helpful. Your response reinforces what I overlooked. I need to sign the package installer just like I would an app but with a Developer ID Installer (not 3rd Party Mac Developer Installer), thus starting my line with productsign --sign 'Developer ID Installer: MyName (######7RBW)' This worked fine after I obtained the Developer ID certificate and added it to my keychain. The syntax for uploading package for notarization. The package installer has now been notarized--I just need to check it on a different machine. Thank so much.

I assume I need to staple as I would a notarized app?

I checked and my Developer ID Installer trust settings were set as you suggested. I was unable to staple using xcrun even though the .pkg was notarized.

@Eskimo: I checked and my Developer ID Installer trust settings were set as you suggested. I was unable to staple using xcrun even though the .pkg was notarized.

Update again. I looked at the installer log, and found the following message about a "Package Authoring Error" that resulted from trying to launch the installer. The actual name of my program is EEG Network Explorer. 2022-05-12 15:02:01-04 fishbacpK0ML85 Installer[8547]: Package Authoring Error: <background_scaling> has an unsupported MIME type: X-NSObject/NSNumber

Was this ever resolved? It's pertinent to my post at Here

Quinn, if it helps the installer log yields another error, IFJS: *** exception: SyntaxError: Unexpected identifier 'Connectivity'. Expected an opening '(' before a function's parameter list. Could this be the source of a javascript error?