The company provided the following statement to Rene Ritchie confirming the fix...
We have identified and fixed an issue with the firmware on the Apple T2 security chip that prevented a very small number of users from booting up their Mac after updating macOS. The updated firmware is now included with the existing macOS updates. Any users impacted by this issue can contact Apple Support for assistance.
You can find instructions on how to make an install key for macOS Monterey here:
● How to Make a Bootable macOS Monterey USB Install Key [Video]
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